Patent Publication Number: US-2023147348-A1

Title: Pump control device and pump control system

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims priority to Japanese Patent Application No. 2020-064576 (entitled “PUMP CONTROL DEVICE AND PUMP CONTROL SYSTEM”) filed on Mar. 31, 2020. The entire contents of the above-listed application are hereby incorporated by reference for all purposes. 
    
    
     TECHNICAL FIELD 
     The present invention generally relates to control devices, in particular to a control device for a pump using a vibration actuator which can perform resonance drive. 
     BACKGROUND 
     Conventionally, for example, pumps disclosed by patent documents 1, 2 or the like have been known as a pump using an actuator which can drive at its resonance frequency. 
     The pump of the patent document 1 uses the actuator to displace a movable wall such as a piston and a diaphragm. This displacement of the movable wall changes a volume in a pump chamber in order to flow working fluid into the pump chamber and discharge the working fluid from the pump chamber. In this pump, a movement cycle of the movable wall itself is changed according to a displacement time, a displacement amount or a displacement speed of the movable wall in a step of compressing the volume in the pump chamber. 
     Further, a pump device of the patent document 2 includes variation imparting means for imparting a predetermined variation to one or more parameters of a frequency, an amplitude and a phase of an alternating-current voltage to be applied to a vibrating body, and frequency response characteristic measuring means for obtaining a frequency response characteristic at one or more predetermined frequencies, which can receive the variation outputted by the variation imparting means as an input and output a physical quantity which can change according to vibration of the vibrating body. This pump device is controlled so that a frequency range of the alternating-current voltage outputted by alternating-current voltage generating means is determined according to an estimated value of a resonance frequency outputted from resonance frequency estimating means. 
     RELATED ART DOCUMENTS 
     Patent Documents 
     Patent document 1: JP 4396095B 
     Patent document 2: JP 2012-135174A 
     SUMMARY 
     Problems to be Solved by the Invention 
     In this regard, while a pump device has been recently downsized, there are needs that a pump of the pump device can provide large pump pressure and large pump flow rate. However, it is required for the pump of the patent document 1 to measure the displacement amount, the displacement speed or the like of the movable wall. Thus, in order to enable the measurement of the displacement amount, the displacement speed or the like of the movable wall, it is required to provide a measurement part for measuring the displacement amount or the displacement speed of the movable wall in the pump. In a case of providing the measurement part in the pump, there is a problem that it is difficult to downsize the pump because an arrangement space for the measurement part needs to be ensured. Further, the configuration of the patent document 2 needs to perform some processes such as a process for obtaining the frequency response characteristic at the one or more of the predetermined frequencies with respect to the physical quantity which can change according to the vibration of the vibrating body and a process for estimating the resonance frequency of the vibrating body which can change according to a parameter change of a drive voltage. Thus, there is a problem that the configuration of the patent document 2 takes a lot of control time. 
     The present invention has been made in view of the above-described conventional problems. Accordingly, it is an object of the present invention to provide a pump control device and a pump control system which can be downsized, ensure more preferable pump pressure and pump flow rate, and stably drive. 
     Means for Solving the Problems 
     This object is achieved by the present inventions as defined in the following (1) to (7). 
     (1) A pump control device for controlling a pump, 
     wherein the pump includes: 
     a vibration actuator for vibrating a vibrating body due to electromagnetic drive caused by electrical current supply to a coil, 
     a sealed chamber which includes a movable wall which can be displaced by vibration of the vibrating body so that a volume in the sealed chamber can be changed by displacement of the movable wall and fluid can be suctioned into an inside of the sealed chamber or discharged from the inside of the sealed chamber when the volume in the sealed chamber is changed, and 
     a discharge portion for communicating the fluid between the sealed chamber and a tank for storing the fluid discharged from the sealed chamber therein to increase pressure of the fluid, and 
     wherein the pump control device comprises: 
     an obtaining part for obtaining pressure value information indicating a value of the pressure of the fluid in the tank or a value corresponding to the pressure, and 
     a control unit for controlling a drive frequency of an electrical current to be supplied to the coil based on the obtained pressure value information. 
     (2) The pump control device according to the above (1), wherein the control unit controls the drive frequency so that the electrical current is supplied to the coil with a resonance frequency of the vibrating body which can be changed according to the pressure of the fluid in the tank. 
     (3) The pump control device according to the above (2), wherein the control unit switches the drive frequency between a first drive frequency for maximizing a flow rate of the fluid from the pump into the tank and a second drive frequency for maximizing the pressure of the fluid in the tank. 
     (4) The pump control device according to the above (3), wherein the control unit switches the drive frequency from the first drive frequency to the second drive frequency in a phase of increasing the pressure of the fluid in the tank. 
     (5) A pump control system, comprising: 
     the pump control device defined by the above (1); 
     the pump; and 
     a pressure detection unit for measuring the pressure of the fluid in the tank to obtain the pressure value information indicating the value of the pressure, 
     wherein the obtaining part obtains the pressure value information from the pressure detection unit. 
     A pump control system, comprising: 
     the pump control device defined by the above (1); 
     the pump; and 
     a timer for measuring a drive time of the vibrating body while the pressure of the fluid in the tank is increased to obtain the pressure value information indicating the drive time, 
     wherein the obtaining part obtains the pressure value information from the timer. 
     (7) The pump control system according to the above (6), wherein the pump control device contains a storage part for storing a table indicating a relationship between a previously set drive time of the vibrating body and the pressure of the fluid in the tank, 
     wherein the pressure of the fluid in the tank increases according to the drive time, and 
     wherein the control unit uses the table to control the drive frequency. 
     Effects of the Invention 
     According to the present invention, it is possible to provide a pump which can be downsized, ensure more preferable pump pressure and pump flow rate, and stably drive. 
    
    
     
       BRIEF DESCRITION OF THE FIGURES 
         FIG.  1    is a block diagram showing a schematic configuration of a pump control system according to a first embodiment of the present invention. 
         FIG.  2    is an external perspective view of a pump of the pump control system according to the first embodiment of the present invention. 
         FIG.  3    is a planar view showing a main configuration of the pump of the pump control system according to the first embodiment of the present invention. 
         FIG.  4    is an exploded perspective view of the pump of the pump control system according to the first embodiment of the present invention. 
         FIG.  5    is a perspective view of a coil core portion in the pump of the pump control system according to the first embodiment of the present invention. 
         FIG.  6    is a perspective view of a vibrating body in the pump of the pump control system according to the first embodiment of the present invention. 
         FIG.  7    is a horizontal cross-sectional view showing an internal configuration of the pump of the pump control system according to the first embodiment of the present invention. 
         FIG.  8    is an exploded perspective view of a pump unit in the pump of the pump control system according to the first embodiment of the present invention. 
         FIG.  9    is a view showing an air flow path of the pump unit of the pump of the pump control system according to the first embodiment of the present invention. 
       Each of  FIG.  10 A  and  FIG.  10 B  is a view showing a discharge and suction operation for air in the pump of the pump control system according to the first embodiment of the present invention. 
         FIG.  11    is a view showing a magnetic spring of the pump of the pump control system according to the first embodiment of the present invention. 
         FIG.  12    is a view showing a configuration of a magnetic circuit of the pump of the pump control system according to the first embodiment of the present invention. 
       Each of  FIG.  13 A  and  FIG.  13 B  is a view showing an operating principle of the pump. 
         FIG.  14    is a view showing frequency characteristics of pressure of air in a tank in a pump-opened state and a pump-closed state when a resonance type pump of the present embodiment is used. 
         FIG.  15    is a view showing one example of frequency control for the pump control system according to the present embodiment of the present invention. 
         FIG.  16    is a view showing a frequency control flow of the pump control system according to the present embodiment of the present invention. 
         FIG.  17    is a block diagram showing a schematic configuration of a pump control system according to a second embodiment of the present invention. 
         FIG.  18    is a view showing a pattern of a drive frequency control in a case where a tank volume is different. 
         FIG.  19    is a view showing another pattern of the drive frequency control in a case where the tank volume is further different. 
         FIG.  20    is a view showing a table in a case where a drive frequency is switched according to a pressure value with the pump control system of the first embodiment. 
       Each of  FIG.  21 A  and  FIG.  21 B  is a view showing a table in a case where the drive frequency is switched according to a time with the pump control system of the first embodiment. 
         FIG.  22    is a view showing a pattern of the frequency control pattern in the first embodiment and the second embodiment. 
         FIG.  23    is a view showing a table in a case where the drive frequency is switched according to the pressure value with the pump control system of the first embodiment. 
         FIG.  24    is a view showing a table in a case where the drive frequency is switched according to the time with the pump control system of the first embodiment. 
         FIG.  25    is a view schematically showing a pump control system according to a third embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, description will be given to embodiments of the present invention with reference to the accompanying drawings. 
     First Embodiment 
     Entire Configuration of Pump Control System  100   
       FIG.  1    is a block diagram showing a schematic configuration of a pump control system  100  according to the present embodiment of the present invention. As shown in  FIG.  1   , the pump control system  100  according to the present embodiment contains a pump  1 , a tank unit  120 , a pressure measurement unit (pressure detection unit)  130 , and a microcomputer unit (control unit)  140 . 
     The pump control system  100  is configured to be able to adjust pressure of fluid (air (gas) in the present embodiment) in a tank unit  120  and then output the fluid. The fluid is discharged from a pump  1 . 
     A frequency of the pump  1  is controlled by a drive signal (electrical current supply) outputted from the microcomputer unit  140 . Specifically, a vibration actuator constituting the pump  1  is electromagnetically driven when the drive signal of a resonance frequency is inputted to the vibration actuator to supply the air which is the fluid into the tank unit  120 . First, description will be given to one example of the pump  1  with reference to  FIGS.  2  to  11   . 
     Entire Configuration of Pump  1   
       FIG.  2    is an external perspective view of the pump unit of the pump of the pump control system according to the first embodiment of the present invention.  FIG.  3    is a planar view showing a main configuration of the pump of the pump control system according to the first embodiment of the present invention.  FIG.  4    is an exploded perspective view of the pump of the pump control system according to the first embodiment of the present invention.  FIG.  5    is a perspective view of a coil core portion in the pump of the pump control system according to the first embodiment of the present invention.  FIG.  6    is a perspective view of a vibrating body in the pump of the pump control system according to the first embodiment of the present invention.  FIG.  7    is a horizontal cross-sectional view showing an internal configuration of the pump of the pump control system according to the first embodiment of the present invention.  FIG.  8    is an exploded perspective view of a pump unit in the pump of the pump control system according to the first embodiment of the present invention. 
     When description is given to the pump with reference to  FIGS.  2  to  8    and  FIGS.  9  to  12   , it is assumed that a vibration direction of a vibrating body which performs reciprocating rotation in a vibration actuator of the pump of the pump control system is defined as a direction shown in  FIG.  3   . The description will be given with assuming that two directions perpendicular to this direction are respectively defined as a horizontal direction (a left-right direction) and a height direction (a vertical direction, also referred to as a thickness direction). Further, in the present embodiment, each expression indicating the directions such as “left-right (lateral)” and “height (vertical)” used to explain a configuration and operation of each part of the pump  1  is not an absolute expression but a relative expression. Although these expressions are appropriate when each part of the pump take a posture shown in each figure, these expressions should be appropriately interpreted depending on the posture of each part of the pump if the posture is changed. 
     The pump  1  shown in  FIG.  2    and  FIG.  3    can discharge the air by utilizing an action of a vibration actuator  10  which can be electromagnetically driven. Although the description will be given with assuming that the pump has a function of discharging and suctioning air in the present embodiment, a target object to be discharged and suctioned by the pump is not limited to air as long as it is fluid. In particular, it is preferable that the target object to be discharged and suctioned by the pump is gas. 
     As shown in  FIG.  2   , the pump  1  has a flat plate-like shape in which a height (a length in the vertical direction in the drawings, which corresponds to a thickness) is shorter than both of a horizontal length (a length in the left-right direction in the drawings) and a vertical length (a length in the depth direction in the drawings, which can be also referred to as the vibration direction). Further, the vertical length is shorter than the horizontal length. In this regard,  FIG.  2    is the perspective view of the pump  1  viewed from a rear side thereof. 
     The pump  1  includes the vibration actuator  10  in which a vibrating body (a movable body)  30  is provided so as to freely perform reciprocating rotation with respect to a fixed body  20  through a shaft portion  40  and pump units  80  ( 80   a ,  80   b ) for discharging and suctioning air due to driving of the vibration actuator  10 . 
     In the present embodiment, the vibrating body  30  is provided in a case  21  of the fixed body  20  through the shaft portion  40  so that the vibrating body  30  can freely perform the reciprocating rotation. 
     Due to a collaborative work of core portions  60  ( 60   a ,  60   b ) around which coils  50   a ,  50   b  are respectively wound and magnets  70  ( 70   a ,  70   b ), the vibrating body  30  can reciprocate (that is, vibrate) with respect to the fixed body  20  along an axial direction of the shaft portion  40 . The pump  1  can discharge and suction the air through a discharge portion  86  by utilizing vibration of the vibrating body  30 . 
     In the pump  1 , the vibrating body  30  is provided in the case  21  having a rectangular shape in a planar view thereof so that the vibrating body  30  can freely perform the reciprocating rotation around the shaft portion  40  disposed at a center of the case  21 . The magnets  70   a ,  70   b  are respectively provided on the inner surface sides of both wall portions of the case  21  separated from each other in a longitudinal direction of the vibrating body  30 . A coil core portion  62   a  including the coil  50   a  and the core portion  60   a  is provided on an inner surface of the wall portion of the case  21  of the fixed body  20  which faces the magnet  70   a . Another coil core portion  62   b  including the coil  50   b  and the core portion  60   b  is provided on an inner surface of the wall portion of the case  21  of the fixed body  20  which faces the magnet  70   b . Each of the magnets  70   a ,  70   b  is preferably a permanent magnet, for example. 
     Vibration Actuator  10   
     The vibration actuator  10  includes the fixed body  20 , the shaft portion  40  and the vibrating body  30  supported by the shaft portion  40  so that the vibrating body  30  can freely perform the reciprocating rotation with respect to the fixed body  20 . Regarding a configuration of the vibration actuator  10 , the magnets  70  ( 70   a ,  70   b ) are provided on one of the fixed body  20  and the vibrating body  30 . Further, the coil core portions  62  ( 62   a ,  62   b ) which are disposed so that magnetized surfaces of cores of each coil core portion  62   a ,  62   b  respectively face the magnets  70  are provided on the other one of the fixed body  20  and the vibrating body  30 . In the present embodiment, the magnets  70   a ,  70   b  are provided on the vibrating body  30  and the coil core portions  62  ( 62   a ,  62   b ) are provided on the fixed body  20 . In other words, the vibrating body  30  includes the magnets  70  ( 70   a ,  70   b ) and the fixed body  20  includes the coil core portions  62  ( 62   a ,  62   b ) in the present embodiment. The vibration actuator  10  can supply an electrical current to the coils  50   a ,  50   b  to electromagnetically drive the vibrating body  30  for vibrating the vibrating body  30  which is a vibrating body. 
     Fixed Body  20   
     The fixed body  20  includes the case  21 , a cover  22  and the coil core portions  62   a ,  62   b . Further, the pump units  80  ( 80   a ,  80   b ) are provided on the fixed body  20 . 
     The case  21  serves as a housing of the pump  1  and has a rectangular box-like shape opened to one side. The shaft portion  40  is provided to stand on the case  21  to pivotally support the movable body  30  disposed in the case  21 . 
     In addition, the coil core portions  62   a ,  62   b  are respectively disposed on the inner surfaces of both wall portions of the case  21  separated from each other in a longitudinal direction of the case  21  so as to respectively face the magnets  70   a ,  70   b  on the vibrating body  30 . 
     The cover  22  covers an opening portion of the case  21 , that is an opening portion opening toward the upper side in the present embodiment. With this configuration, the case  21  and the cover  22  serve as a hollow electromagnetic shield and the pump  1  is formed in a flat plate-like shape. 
     The shaft portion  40  is provided on a center of a bottom surface of the case  21  in the horizontal direction and the depth direction of the case  21  so as to extend in the height direction of the case  21 . The shaft portion  40  is fitted and fixed to a shaft hole  23  of the cover  22  in a state that the shaft portion  40  is passed through a bearing portion  34  of the vibrating body  30  by press-fitting or bonding after the shaft portion  40  is inserted into the shaft hole  23 . With this configuration, the shaft portion  40  is supported in a state that the shaft portion  40  is passed through the bearing portion  34  of the vibrating body  30  and bridged between the bottom surface of the case  21  and the cover  22 . 
     The coil core portions  62   a ,  62   b  are respectively disposed on the inner surfaces of both wall portions of the case  21  separated from each other in the longitudinal direction of the case  21  so as to face each other. Further, the coil core portions  62   a ,  62   b  are disposed so as to sandwich the vibrating body  30  in the longitudinal direction of the case  21 . 
     In the present embodiment, the coil core portions  62   a ,  62   b  are configured so as to have the same configuration and respectively provided at positions symmetrical around an axis of the shaft portion  40  in the planar view. 
     The core portions  60   a ,  60   b  are magnetic bodies which can be magnetized when an electrical current flows in the coils  50   a ,  50   b . The core portions  60   a ,  60   b  may be made of electromagnetic stainless material, sintered material, metal injection mold (MIM) material, a laminated steel sheet, an electrogalvanized steel sheet (SECC) or the like. In the present embodiment, each of the core portions  60   a ,  60   b  is constituted of laminated cores made of the laminated steel sheet. 
     The core portions  60   a ,  60   b  respectively have cores  601   a ,  601   b  around which the coils  50   a ,  50   b  are respectively wound and magnetic poles (hereinafter, for convenience, referred to as “core magnetic poles”)  602   a ,  603   a ,  602   b ,  603   b  formed continuously with both end portions of the cores  601   a ,  601   b.    
     In the present embodiment, each of the core magnetic poles  602   a ,  603   a ,  602   b ,  603   b  has a magnetic pole surface curved so as to have an arc planar shape corresponding to a shape of a magnetized surface of each of the magnets  70   a ,  70   b  which can perform reciprocating rotation. 
     The core magnetic poles  602   a ,  603   a  of the core portion  60   a  face the magnet  70   a  and the core magnetic poles  602   b ,  603   b  of the core portion  60   b  face the magnet  70   b . The core magnetic poles  602   a ,  603   a ,  602   b ,  603   b  are aligned in a rotation direction of the reciprocating rotation of the vibrating body  30 . 
     The core magnetic poles  602   a ,  603   a ,  602   b ,  603   b  are preferably disposed on a circumference of a circle around the shaft portion  40 . This circumference is a circumferential track along a movement track of the magnets  70   a ,  70   b.    
     In the coil core portions  62   a ,  62   b , the core magnetic poles  602   a ,  603   a ,  602   b ,  603   b  of the core portions  60   a ,  60   b  around which the coils  50   a ,  50   b  are respectively wound are disposed so as to face a magnetization direction of the magnets  70   a ,  70   b.    
     The coils  50   a ,  50   b  in the core portions  60   a ,  60   b  are connected to, for example, a power supply unit (not shown). When the electrical current is supplied from the power supply unit to the coils  50   a ,  50   b , the core magnetic poles  602   a ,  603   a ,  602   b ,  603   b  are excited. When the core magnetic poles  602   a ,  603   a ,  602   b ,  603   b  are excited, the core magnetic poles  602   a ,  602   b  are excited so as to have a polarity differing from a polarity of the core magnetic poles  603   a ,  603   b  in each of the core portions  60   a ,  60   b.    
     Vibrating Body  30   
     As shown in  FIG.  3   ,  FIG.  4   ,  FIG.  6    and  FIG.  7   , the vibrating body  30  is disposed in the case  21  of the fixed body  20  so as to extend in a direction (the longitudinal direction of the case  21 ) perpendicular to the shaft portion  40  (the rotational axis of the vibrating body  30 ). 
     The vibrating body  30  is supported in the case  21  so that the vibrating body  30  can freely perform the reciprocating rotation around the shaft portion  40 . The vibrating body  30  includes a vibrating body main portion  32 , the bearing portion  34 , the pair of magnets  70   a ,  70   b  disposed so that the plurality of magnetic poles (three magnetic poles in the present embodiment) of each of the magnets  70   a ,  70   b  are alternately disposed in the rotation direction (the depth direction) and pressing portions  35 . 
     The bearing portion  34  is fixed to the vibrating body main portion  32  and the shaft portion  40  is passed through the bearing portion  34 . The pair of magnets  70   a ,  70   b  are fixed to the vibrating body main portion  32  so as to sandwich the shaft portion  40  passed through the bearing portion  34 . 
     The vibrating body main portion  32  may or may not be a magnetic body (a ferromagnetic body). In the present embodiment, the vibrating body main portion  32  is a yoke and serves as a weight of the vibrating body  30 . The vibrating body main portion  32  is constituted by laminating yoke iron cores, for example. The constituent material of the vibrating body main portion  32  is not limited to metal material. Resin material or the like may be used as the constituent material of the vibrating body main portion  32 . 
     The vibrating body main portion  32  has a center opening portion  322  formed at a center portion of the vibrating body main portion  32  and to which the bearing portion  34  is fixed and arm portions  324   a ,  324   b  respectively extending in opposite directions from the center portion. Each of the arm portions  324   a ,  324   b  has an elongated flat plate-like shape and end portions of the arm portions  324   a ,  324   b  are formed so as to protrude in a direction perpendicular to the extending direction. Further, magnet fixing portions  326   a ,  326   b  are respectively formed on tip end surfaces of the arm portions  324   a ,  324   b.    
     A tip end surface of each of the magnet fixing portions  326   a ,  326   b  is formed to be curved in an arc shape. The magnets  70   a ,  70   b  are respectively fixed to the tip end surfaces of the magnet fixing portions  326   a ,  326   b . The pressing portions  35  are respectively provided on the arm portions  324   a ,  324   b.    
     Magnets  70   a ,  70   b    
     The magnets  70   a ,  70   b  constitute magnetic circuits for driving the vibration actuator  10  together with the coil core portion  62   a ,  62   b  which are disposed to respectively face the magnets  70   a ,  70   b.    
     Each of the magnets  70   a ,  70   b  has a magnetic pole surface  72  serving as a plurality of magnetic poles. The magnets  70   a ,  70   b  are disposed so that the magnetic pole surface  72  of the magnet  70   a  and the magnetic pole surface  72  of the magnet  70   b  are directed toward opposite sides through the shaft portion  40 . In the present embodiment, the magnets  70   a ,  70   b  are respectively provided on both end portions of the vibrating body main portion  32  through which the shaft portion  40  is passed through at the center portion thereof. The end portions of the vibrating body main portion  32  are separated from each other in the extending direction of the vibrating body main portion  32 . Namely, the magnets  70   a ,  70   b  are respectively provided on tip end portions of the arm portions  324   a ,  324   b  so that the magnetic pole surfaces  72  of the magnets  70   a ,  70   b  are directed toward the outside. 
     As shown in  FIGS.  3  to  7    and  FIG.  11   , the magnetic pole surface  72  contains three different magnetic poles  721 ,  722 ,  723  alternately disposed. In this regard, each of the magnets  70   a ,  70   b  may be configured by alternately arranging magnets (magnet pieces) having different magnetic poles or may be magnetized so as to have different magnetic poles alternately disposed in the rotation direction. The magnets  70   a ,  70   b  are constituted of, for example, Nd sintered magnets or the like. 
     The magnetic poles  721 ,  722 ,  723  of each of the magnets  70   a ,  70   b  are disposed so as to be adjacent to each other in the depth direction perpendicular to an axis line of the shaft portion  40  through the shaft portion  40 , that is, in the rotation direction. 
     The magnets  70   a ,  70   b  are respectively disposed on both end portions of the vibrating body  30  so that the magnetic pole surfaces  72  of the magnets  70   a ,  70   b  are positioned on the circumference of the circle around the shaft portion  40 . The magnets  70   a ,  70   b  are provided so that a center position of a length of the center magnetic pole  722  of each of the magnetic pole surfaces  72  in the rotation direction is positioned at a center position between the core magnetic poles  602   a ,  603   a  in a normal state, that is, in a non-energization state that the electrical current is not supplied to the coils  50   a ,  50   b.    
     In the present embodiment, the magnets  70   a ,  70   b  are disposed on the vibrating body  30  so as to respectively face the coil core portions  62   a ,  62   b  respectively provided on the inner surfaces of both wall portions of the housing (the case  21 ) and at positions which are farthest apart from the shaft portion  40  through the arm portions  324   a ,  324   b.    
     Pressing Portion  35   
     The pressing portions  35  press movable walls  822  of a pair of sealed chambers  82  of the pump units  80  when the vibrating body  30  performs rotational movement. Specifically, each of the pressing portions  35  includes a pair of pushers  351  for pressing the movable walls  822  of the pair of the sealed chambers  82  when the arm portions  324   a ,  324   b  perform the reciprocating rotation. 
     The pairs of pushers  351  of the pressing portions  35  are respectively provided on the arm portions  324   a ,  324   b  so as to protrude in the width direction, that is, in the rotation direction of the arm portions  324   a ,  324   b . Each of the pressing portions  35  may be formed so as to linearly press the movable wall  822  in a facing direction even when the vibrating body  30  rotates, for example. In the present embodiment, each pusher  351  of the pressing portions  35  moves in an arc track around the shaft portion  40  and abuts against the movable wall  822  to press the movable wall  822 . The pressing portion  35  may be configured in any manner as long as it is configured to be displaced toward the movable wall side when the vibrating body  30  performs the rotational movement to press and move the movable wall  822 . Preferably, the movable wall  822  is disposed so as to intersect a movement track of the pressing portion  35  and the moving pressing portion  35  is disposed so as to make surface-contact with the movable wall  822 . 
     For example, as shown in  FIG.  10   , the pressing portion  35  is fixed with respect to each of the arm portions  324   a ,  324   b  through a shaft protrusion  353  axially attached to a round hole  328  so that the shaft protrusion  353  can perform pivotal movement and a guide protrusion  352  guided by a long hole  329 . With this configuration, the pusher  351  swings in the arc track when the vibrating body  30  performs the reciprocating rotation. For example, a tip end of the pusher  351  may swing by loosely fitting the guide protrusion  352  into the long hole  329  to allow the pressing portion  35  to swing with respect to the arm portions  324   a ,  324   b  through the guide protrusion  352 . In this case, although the pressing portion  35  moves in the arc track when the vibrating body  30  rotates, the pusher  351  can linearly move with respect to the movable wall  822  to press the movable wall  822 . 
     In the present embodiment, the pressing portion  35  is connected to the movable wall  822  of the pump unit  80  through the pusher  351 . The pusher  351  is inserted into an insertion portion  822   a  of the movable wall  822  serving as a diaphragm when the vibrating body  30  performs the rotational movement to push and displace the movable wall  822  in the rotation direction. The pressing portion  35  moves toward the side of the movable wall  822  to press the movable wall  822  when the vibrating body  30  rotates. Further, when the vibrating body  30  oppositely rotates, the pressing portion  35  moves toward the side opposite to the movable wall  822  and gradually decreases pressure with respect to the movable wall  822  to displace the movable wall  822  in a direction opposite to the pressing direction. 
     The bearing portion  34  is constituted of a sintered sleeve bearing, for example. The bearing portion  34  is fitted into the center opening portion  322  of the vibrating body main portion  32  so that the shaft portion  40  is positioned on a center axis of the vibrating body main portion  32 . 
     When the electrical current is not supplied to the coils  50   a ,  50   b , the vibrating body main portion  32  is biased so as to be positioned at a center of the case  21  (the fixed body  20 ) in the longitudinal direction by functions of magnetic springs provided by the core portions  60   a ,  60   b  and the magnets  70   a ,  70   b.    
     Pump Unit  80   
     Each of the pump units  80  ( 80   a ,  80   b ) includes the movable walls  822 , the sealed chambers  82  defined by the movable walls  822 , a suction portion  83 , valves  84 , the discharge portion  86  and a discharge flow path portion  88 . 
     Movable Wall  822   
     The movable wall  822  forms a wall portion for partitioning between a chamber forming portion  824  and the discharge flow path portion  88  and is provided so as to be displaceable. The movable wall  822  is displaced to change a volume in the sealed chamber  82  when the vibrating body  30  vibrates. The movable wall  822  constitutes the sealed chamber  82  together with the chamber forming portion  824 . 
     The movable wall  822  is formed of, for example, elastically deformable material and is provided so as to close the chamber forming portion  824 . For example, the movable wall  822  is a diaphragm. 
     The movable wall  822  has the insertion portion  822   a  into which the pusher  351  of the pressing portion  35  is inserted and is connected to the pressing portion  35  through the insertion portion  822   a . The movable wall  822  is displaced when the movable wall  822  is pressed by the pressing portion  35  which moves in accordance with the rotation of the vibrating body  30 . 
     The movable wall  822  is elastically deformed when the movable wall  822  is pressed toward the chamber forming portion  824  by the pressing portion  35  through the insertion portion  822   a  and deformed to reduce a volume of the chamber forming portion  824 . Since the movable wall  822  is displaced toward the chamber forming portion  824  and protrudes into the chamber forming portion  824 , the movable wall  822  can change the volume in the sealed chamber  82 . 
     The movable wall  822  is inserted into the chamber forming portion  824  by one-side rotation movement (swing to one side of the rotation direction) of the reciprocating rotation of the vibrating body  30  to press the inside of the chamber forming portion  824  and reduce the volume in the sealed chamber  82  for discharging the air. On the other hand, when the vibrating body  30  rotates in the other side (moves toward the other side of the rotation direction), the movable wall  822  increases the volume in the sealed chamber  82  to suction the air. 
     Sealed Chamber  82   
     The sealed chamber  82  is a sealed space to which the suction portion  83  and the discharge portion  86  are connected and whose volume can be changed by the displacement of the movable wall  822 . The discharge portion  86  has a discharge port communicated with the outside and discharges the air from the pump  1  to the outside through the discharge port. For example, the discharge port may be an opening communicated with the discharge portion  86  connected to a bottom surface of the sealed chamber  82 . When the movable wall  822  is displaced, the volume in the sealed chamber  82  is changed. As a result, the air is suctioned into the sealed chamber  82  or the air is discharged to the outside from the inside of the sealed chamber  82 . The discharge portion  86  communicates the fluid between the tank unit  120  and the sealed chamber  82 . 
     In the pump unit  80 , when the movable wall  822  is pressed by the pressing portion  35 , the movable wall  822  is elastically deformed toward the inside of the sealed chamber  82  to press the air in the sealed chamber  82 . The pressed air in the sealed chamber  82  is discharged to the outside through the discharge portion  86 . When the movable wall  822  moves so as to return to an initial position, that is, when the pressed state by the pressing portion  35  is released and the volume in the sealed chamber  82  increases from the pressed state, the air is suctioned from the outside into the sealed chamber  82  through the suction portion  83 . For example, the suction portion  83  has a suction port and can suction the air into the sealed chamber  82  through the suction port. For example, the suction port may be an opening communicated with the suction portion  83  in the chamber forming portion  824 . 
     Each of the pump units  80  ( 80   a ,  80   b ) is disposed in the case  21  along the extending direction of the vibrating body  30 , that is, along side wall portions of the case  21  extending in the longitudinal direction of the case  21 . Further, the pump units  80  ( 80   a ,  80   b ) are disposed so as to sandwich the vibrating body main portion  32  of the vibrating body  30  in the depth direction of the case  21 . 
     For example, the pump unit  80  includes a base  801 , a diaphragm portion  802 , a cylinder portion  803 , a valve portion  804 , a valve cover portion  805 , a partition portion  806  and a flow path forming portion  807 . Each of the base  801 , the diaphragm portion  802 , the cylinder portion  803 , the valve portion  804 , the valve cover portion  805 , the partition portion  806  and the flow path forming portion  807  has an elongated plate-like shape extending in the longitudinal direction of the case  21  and constitutes the pump unit  80  having an internal space sealed by stacking these portions. 
     The base  801  has an opening. The insertion portion  822   a  of the diaphragm portion  802  is passed through the opening of the base  801  from a rear surface side of the base  801  so as to protrude toward a front surface side of the base  801 . The base  801  and the flow path forming portion  807  constitute a housing of the pump unit  80  having a strip shape. The diaphragm portion  802  is formed from elastic material such as rubber. The diaphragm portion  802  has the insertion portion  822   a  and the movable wall  822 . The chamber forming portion  824  of the cylinder portion  803  is disposed on the rear surface side of the movable wall  822  which has flexibility and can be elastically deformed. The diaphragm portion  802  and the cylinder portion  803  are attached to each other so that the movable wall  822  of the diaphragm portion  802  and the chamber forming portion  824  of the cylinder portion  803  define the sealed chamber  82  which is a sealed space. 
     The cylinder portion  803  has the chamber forming portion  824  and two communication holes formed in a surface facing the movable wall  822  in the sealed chamber  82  so as to be respectively communicated with the discharge portion  86  and the suction portion  83 . The two communication holes are respectively connected to the discharge flow path portion  88  and the suction portion  83  of the flow path forming portion  807  and the valve cover portion  805  through the valves  84  of the valve portion  804  which are attached from the rear surface side of the cylinder portion  803  so as to overlap with the two communication holes. 
     The valve portion  804  is attached to the valve cover portion  805 . The valve  84  connected to the discharge portion  86  is configured to communicate with the discharge portion  86  of the flow path forming portion  807  when the volume in the sealed chamber  82  decreases. On the other hand, the valve  84  connected to the discharge portion  86  is configured to be closed when the volume in the sealed chamber  82  increases. The valve  84  connected to the suction portion  83  is configured to be closed when the volume in the sealed chamber  82  decreases. On the other hand, the valve  84  connected to the suction portion  83  is configured to communicate with the suction portion  83  of the flow path forming portion  807  when the volume in the sealed chamber  82  increases. 
     In the present embodiment, each of the pump units  80  ( 80   a ,  80   b ) has the pair of sealed chambers  82  each constituted of the chamber forming portion  824  and the movable wall  822 . Each of the pump units  80  ( 80   a ,  80   b ) is disposed so that its own pair of sealed chambers  82  respectively face side surfaces of the arm portions  324   a ,  324   b  extending in directions opposite to each other through the shaft portion  40 . Namely, the pump units  80  ( 80   a ,  80   b ) are disposed so as to face each other at positions where the arm portions  324   a ,  324   b  are sandwiched between the pairs of sealed chambers  82  of the pump units  80  ( 80   a ,  80   b ) in the direction of the reciprocation and rotation movement of the arm portions  324   a ,  324   b.    
     Each of  FIG.  10 A  and  FIG.  10 B  is a view showing an air discharge operation or an air suction operation of the pump of the pump control system according to the first embodiment of the present disclosure. 
     When the pressing portion  35  moves toward the movable wall  822 , the pusher  351  contacts and presses the movable wall  822  through the insertion portion  822   a  as shown in  FIG.  10 A . As a result, the movable wall  822  is displaced toward the side of the chamber forming portion  824  and thus the air in the sealed chamber  82  is pressed and compressed. The compressed air flows to the side of the discharge portion  86  which is only one communicated with the sealed chamber  82  through the opened valve  84  (see white arrows in  FIG.  10 A ). 
     On the other hand, when the pressing portion  35  reversely moves in the rotation direction, that is, moves away from the side of the pump unit  80 , the movable wall  822  elastically returns in accordance with the movement of the pressing portion  35  and the volume in the sealed chamber  82  is returned, that is, increased as shown in  FIG.  10 B . At this time, the valve  84  connected to the discharge portion  86  is tightened to close the discharge path and the valve  84  connected to the suction portion  83  is opened. Thus, the air is suctioned into the sealed chamber  82  through the suction portion  83  (indicated by white arrows in the  FIG.  10 B ). 
     Magnetic Circuit Configuration 
     In the present embodiment, the core portions  60   a ,  60   b  which are magnetic members are disposed in the case  21  so as to respectively face the magnets  70   a ,  70   b  with being apart from the magnets  70   a ,  70   b  in the longitudinal direction as shown in  FIG.  3    and  FIG.  7   . The magnets  70   a ,  70   b  are respectively disposed at both ends of the vibrating body  30  so as to face each other through the shaft portion  40 . The core portions  60   a ,  60   b  are respectively disposed on inner surfaces of both wall portions of the case  21  in the longitudinal direction so as to face each other with being apart from each other in the longitudinal direction. 
     Magnetic attraction force is generated between the core portion  60   a  and the magnet  70   a  and between the core portion  60   b  and the magnet  70   b . Since these two kinds of magnetic attraction force generated in the longitudinal direction (the extending direction of the arm portion  324   a ,  324   b ) are generated in opposite directions on one straight line through the shaft portion  40 , these two kinds of magnetic attraction force cancel each other. 
       FIG.  11    is a view showing a magnetic spring of the pump of the pump control system according to the first embodiment of the present invention. In the pump  1 , a magnetic circuit provided by the coil core portion  62   a  and the magnet  70   a  and a magnetic circuit provided by the coil core portion  62   b  and the magnet  70   b  are configured to be point-symmetrically around the shaft portion  40 . Thus, only the magnetic circuit provided by the coil core portion  62   a  and the magnet  70   a  will be described in  FIG.  11    and description for the magnetic circuit provided by the coil core portion  62   b  and the magnet  70   b  will be omitted. 
     In  FIG.  11   , the magnet  70   a  has a configuration in which the magnetic poles  721 ,  722 ,  723  on the magnetic pole surface  72  facing the core portion  60   a  are respectively magnetized as N pole, S pole and N pole. Each of the magnetic poles  721  to  723  on the magnetic pole surface  72  of the magnet  70   a  respectively attracts the core magnetic poles  602   a ,  603   a  close to each of the magnetic poles  721  to  723 . 
     The center magnetic pole  722  of the magnet  70   a  attracts both of the core magnetic poles  602   a ,  603   a . The magnetic pole  721  of the magnet  70   a  attracts the core magnetic pole  602   a . The magnetic pole  723  of the magnet  70   a  attracts the core magnetic pole  603   a . As a result, the center magnetic pole  722  of the magnet  70   a  is located at the center of the coil core portion  62   a , that is, at a position between the core magnetic poles  602   a ,  603   a.    
     In the pump  1 , when the electrical current flows in the coil  50   a  of the coil core portion  62   a , the core magnetic poles  602   a ,  603   a  of the core portion  60   a  are excited with different polarities. As a result, thrust force is generated with respect to the vibrating body  30  in accordance with the relationship with the magnet  70   a  disposed so as to face the coil core portion  62   a . The same discussion can be applied to the magnetic circuit provided by the coil core portion  62   b  and the magnet  70   b . By periodically changing the direction of the electric current supplied to the coils  50   a ,  50   b , the vibrating body  30  including the magnets  70   a ,  70   b  performs the reciprocating rotational movement (reciprocating rotational vibration) in the rotation direction around the shaft portion  40 . 
     Operation of Pump  1   
     An example of the operation of the pump  1  will be described with reference to  FIG.  12   .  FIG.  12    is a view showing the magnetic circuit configuration of the pump of the pump control system  100  according to the first embodiment of the present invention. In this regard, similarly to the description with reference to  FIG.  11   , only the magnetic circuit provided by the coil core portion  62   a  and the magnet  70   a  will be described in the description for the example of the operation of the pump  1  with reference to  FIG.  12    and description for the magnetic circuit provided by the coil core portion  62   b  and the magnet  70   b  will be omitted. 
     It is assumed that the magnet  70   a  has three different polarities on the magnetic pole surface  72  so that the three different polarities are alternately arranged in the rotation direction of the vibrating body  30 . In the magnet  70   a  shown in  FIG.  12   , the central magnetic pole  722  is the S pole and each of the magnetic poles  721 ,  723  sandwiching the center magnetic pole  722  is the N pole on the magnetic pole surface  72  facing the core portion  60   a.    
     When the electrical current is supplied to the coil  50   a  of the coil core portion  62   a  to excite the core portion  60   a , the core magnetic pole  602   a  of the core portion  60   a  is magnetized with the S pole and the core magnetic pole  603   a  of the core portion  60   a  is magnetized with the N pole as shown in  FIG.  12   . 
     Since the magnetic pole  723  of the magnet  70   a  magnetized with the N pole faces the core magnetic pole  603   a  magnetized with the N pole as shown in  FIG.  12   , the magnetic pole  723  of the magnet  70   a  repels with respect to the core magnetic pole  603   a . In addition, since the magnetic pole  722  of the magnet  70   a  is magnetized with the S pole, magnetic attraction force is generated between the magnetic pole  722  and the core magnetic pole  603   a  magnetized with the N pole and the magnetic pole  722  repels with respect to the core magnetic pole  602   a  magnetized with the S pole. Further, since the magnetic pole  721  of the magnet  70   a  is magnetized with the N pole, magnetic attraction force is generated between the magnetic pole  721  and the core magnetic pole  602   a  magnetized with the S pole. 
     With this configuration, thrust force in the direction F 1  is generated between the magnet  70   a  and the coil core portion  62   a , and thereby the vibrating body  30  is driven in the direction F 1 . In a state that the electrical current is not supplied to the coil  50   a , the vibrating body  30  is located at a rotation reference position, that is a neutral position for the reciprocation movement by the magnetic attraction force of the magnetic spring. 
     Further, the electrical current is supplied to the coil  50   a  in the opposite direction to reverse the polarity of the core portion  60   a . Namely, the magnetic pole  603   a  of the core portion  60   a  facing the magnet  70   a  is magnetized with the S pole and the magnetic pole  602   a  of the core portion  60   a  is magnetized with the N pole. As a result, the magnet  70   a  facing the core portion  60   a  rotates in a direction (direction −F 1 ) opposite to the direction F 1 . The vibrating body  30  is driven in the direction −F 1  which is 180 degrees opposite to the direction F 1 . 
     In the vibrating body  30 , the relationship between the magnet  70   b  disposed on the opposite side of the magnet  70   a  through the shaft portion  40  and the coil core portion  62   b  is point-symmetrical with respect to the relationship between the magnet  70   a  and the coil core portion  62   a  around the shaft portion  40 . Thus, thrust force in the direction F 1  or the direction −F 1  is also generated between the magnet  70   b  and the coil core portion  62   b  similar to the thrust force generated between the magnet  70   a  and the coil core portion  62   a . With this configuration, the vibrating body  30  preferably performs the reciprocating rotation around the shaft portion  40  due to the magnetic attraction force and the repulsion force which are effectively generated in the magnetic circuits at both end portions of the vibrating body  30 . 
     This driving principle will be described in the following description. In the vibration actuator  10 , when an inertial moment of the vibrating body  30  is defined as J [Kg*m 2 ] and a spring constant in the rotation direction is defined as K sp , the vibrating body  30  vibrates with respect to the fixed body  20  with a resonant frequency fr [Hz] calculated by the following equation (1). 
     
       
         
           
             
               
                 
                   Equation 
                   ⁢ 
                       
                   1 
                 
               
               
                  
               
             
             
               
                 
                   
                     f 
                     r 
                   
                   = 
                   
                     
                       1 
                       
                         2 
                         ⁢ 
                         π 
                       
                     
                     ⁢ 
                     
                       
                         
                           K 
                           sp 
                         
                         J 
                       
                     
                   
                 
               
               
                 
                   ( 
                   1 
                   ) 
                 
               
             
           
         
       
     
     In the pump  1 , an alternating current having a frequency substantially equal to the resonant frequency fr of the vibrating body  30  is supplied to the coils  50   a ,  50   b  to excite the core portions  60   a ,  60   b  (more specifically, the core magnetic poles  602   a ,  603   a ,  602   b ,  603   b ) with the coils  50   a ,  50   b . As a result, it is possible to efficiently drive the vibrating body  30 . 
     The vibrating body  30  in the vibration actuator  10  is in a state that it is supported by a spring mass system structure constituted of the magnetic springs provided by the magnets  70   a ,  70   b  and the coil core portions  62   a ,  62   b  respectively having the coils  50   a ,  50   b  and the core portions  60   a ,  60   b . Thus, when the alternating current having the frequency equal to the resonance frequency fr of the vibrating body  30  is supplied to the coils  50   a ,  50   b , the vibrating body  30  is driven in a resonance condition. 
     A motion equation and a circuit equation representing the driving principle of the vibration actuator  10  are shown below. The vibration actuator  10  is driven based on the motion equation expressed by the following equation (2) and the circuit equation expressed by the following equation (3). 
     
       
         
           
             
               
                 
                   Equation 
                   ⁢ 
                       
                   2 
                 
               
               
                  
               
             
             
               
                 
                   
                     J 
                     ⁢ 
                     
                       
                         
                           d 
                           2 
                         
                         ⁢ 
                         
                           θ 
                           ⁡ 
                           ( 
                           t 
                           ) 
                         
                       
                       
                         dt 
                         2 
                       
                     
                   
                   = 
                   
                     
                       
                         K 
                         f 
                       
                       ⁢ 
                       
                         i 
                         ⁡ 
                         ( 
                         t 
                         ) 
                       
                     
                     - 
                     
                       
                         K 
                         sp 
                       
                       ⁢ 
                       
                         θ 
                         ⁡ 
                         ( 
                         t 
                         ) 
                       
                     
                     - 
                     
                       D 
                       ⁢ 
                       
                         
                           d 
                           ⁢ 
                           
                             θ 
                             ⁡ 
                             ( 
                             t 
                             ) 
                           
                         
                         dt 
                       
                     
                   
                 
               
               
                 
                   ( 
                   2 
                   ) 
                 
               
             
           
         
       
     
     J: Inertial moment [Kg*m 2 ] 
     θ(t): Displacement angle [rad] 
     K f : Thrust constant [Nm/A] 
     i(t): Current [A] 
     K sp : Spring constant [Nm/rad] 
     D: Damping coefficient [Nm/(rad/s)] 
     
       
         
           
             
               
                 
                   Equation 
                   ⁢ 
                       
                   3 
                 
               
               
                  
               
             
             
               
                 
                   
                     e 
                     ⁡ 
                     ( 
                     t 
                     ) 
                   
                   = 
                   
                     
                       Ri 
                       ⁡ 
                       ( 
                       t 
                       ) 
                     
                     + 
                     
                       L 
                       ⁢ 
                       
                         
                           di 
                           ⁡ 
                           ( 
                           t 
                           ) 
                         
                         dt 
                       
                     
                     + 
                     
                       
                         K 
                         e 
                       
                       ⁢ 
                       
                         
                           dx 
                           ⁡ 
                           ( 
                           t 
                           ) 
                         
                         dt 
                       
                     
                   
                 
               
               
                   
               
             
           
         
       
     
     e(t): Voltage [V] 
     R: Resistance [Ω] 
     L: Inductance 
     K e : Counter-electromotive force constant [V/(m/s)] 
     Namely, the inertial moment J [Kg*m 2 ], a displacement angle (rotational angle) θ(t) [rad], a thrust constant (torque constant) K f  [Nm/A], an electrical current i(t) [A], the spring constant K sp  [Nm/rad], a damping factor D [Nm/(rad/s)] and the like of the vibrating body  30  in the vibration actuator  10  of the pump  1  can be appropriately changed as long as they satisfy the equation (2). A voltage e(t) [V], a resistance R [Ω], an inductance L[H] and a counter-electromotive force constant K e  [V/(m/s)] can be appropriately changed as long as they satisfy the equation (3). 
     As described above, when the alternating current having the frequency corresponding to the resonance the resonant frequency fr determined by the inertial moment J of the vibrating body  30  and the spring constant K sp  of the magnetic spring is supplied to the coils  50   a ,  50   b , it is possible to efficiently obtain a large vibration output of the vibration actuator  10  of the pump  1 . 
     In the pump  1 , the volume in the sealed chamber  82  is changed by the displacement of the movable wall  822  (specifically, the deformation of the diaphragm) in the pump unit  80  when the vibrating body  30  performs the reciprocating rotation. Thus, the pump  1  can provide a pump function. In the following description, a flow rate of this pump function is set by the following equation (4) and pressure of this pump function is set by the following equation (5). 
       Equation 4 
         Q=Axf* 60   (4)
 
     Q: Flow rate [L/min] 
     A: Piston area [m 2 ] 
     x: Piston displacement [m] 
     f: Drive frequency [Hz] 
     
       
         
           
             
               
                 
                   Equation 
                   ⁢ 
                       
                   5 
                 
               
               
                  
               
             
             
               
                 
                   P 
                   = 
                   
                     
                       P 
                       0 
                     
                     ( 
                     
                       
                         
                           V 
                           + 
                           
                             Δ 
                             ⁢ 
                             V 
                           
                         
                         
                           V 
                           - 
                           
                             Δ 
                             ⁢ 
                             V 
                           
                         
                       
                       - 
                       1 
                     
                     ) 
                   
                 
               
               
                 
                   ( 
                   5 
                   ) 
                 
               
             
           
         
       
     
     P: Increased pressure [kPa] 
     P 0 : Atmospheric pressure [kPa] 
     V: Sealed chamber volume [m 3 ] 
     ΔV: Changed volume [m 3 ] 
     ΔV=Ax 
     A: Piston area [m 2 ] 
     x: Piston displacement [m] 
     Namely, a flow rate Q [L/min], a piston area A [m 2 ], a piston displacement x [m], a drive frequency f [Hz] and the like of the pump  1  can be appropriately changed as long as they satisfy the equation (4). Further, an increasing pressure [kPa], an atmospheric pressure P 0  [kPa], a sealed chamber volume V [m 3 ] and a changed volume ΔV [m 3 ]=the piston area [m 2 ] A * the piston displacement [m] can be appropriately changed as long as they satisfy the equation (5). 
     As described above, the pump  1  of the present embodiment has the vibration actuator  10  which can be electromagnetically driven and the pump units  80  ( 80   a ,  80   b ) which suction and discharge the air due to the electromagnetic drive of the vibration actuator  10 . In the vibration actuator  10 , the fixed body  20  includes one of the coil core portion  62   a  having the coil  50   a  and the core portion  60   a  around which the coil  50   a  is wound and the magnet  70   a  disposed so as to face the end portion of the core portion  60   a . Further, the pump units  80  are provided on the fixed body  20 . The vibrating body  30  includes the other one of the coil core portion  62   a  and the magnet  70   a . Further, the vibrating body  30  is elastically held by the magnetic attraction force of the magnet  70   a . The shaft portion  40  reciprocally and rotatably supports the vibrating body  30 . The pump unit  80   a  includes the movable wall  822  which can be moved by the rotational movement of the vibrating body  30  and the sealed chamber  82  which communicates with the discharge portion  86  for the air and the suction portion  83  for the air and whose volume can be changed by the displacement of the movable wall  822 . The vibrating body  30  has the pressing portions  35  which move in the arc track around the shaft portion  40  when the vibrating body  30  performs the reciprocating rotational movement and contacts with the movable walls  822  to press the movable walls  822 . The movable walls  822  are disposed in the moving direction of the pressing portions  35  and displaced to discharge the air in the sealed chamber  82  through the discharge portion  86  when the movable walls  822  are pressed by the pressing portion  35 . 
     Tank Unit  120   
     Referring back to  FIG.  1   , the tank unit  120  adjusts the pressure of the fluid discharged from the pump  1 . Specifically, the tank unit  120  stores the air discharged from the sealed chambers  82  of the pump  1  therein to increase pressure of the air discharged from the tank unit  120 . The tank unit  120  is connected to a tank discharge flow path and can contain and store the air discharged from the sealed chambers  82  therein without outputting the air to the outside to adjust pressure in the tank unit  120 . The tank unit  120  is connected to the discharge ports  86  of the pump  1  and thus the fluid can communicate between the tank unit  120  and the sealed chambers  82  of the pump  1  (the pump units  80 ). 
     The fluid, which is the air in the present embodiment, discharged from the pump  1  (the pump units  80 ) is supplied into the tank unit  120 . The tank unit  120  may store the supplied fluid to increase the pressure of the fluid in the tank unit  120  and release the air with predetermined pressure. Any arbitrary device can be used as the tank unit  120  as long as it has a volume enough for storing the air to increase the pressure of the fluid discharged from the tank unit  120  and uses the supplied air. For example, the tank unit  120  may be a cuff of a sphygmomanometer. 
     Pressure Measurement Unit  130   
     The pressure measurement unit  130  measures a state of the air (the fluid) in the tank unit  120 . Specifically, the pressure measurement unit  130  measures the pressure of the air (the fluid) in the tank unit  120  to obtain pressure value information indicating a value of the pressure and outputs the pressure value information to the microcomputer unit  140 . The pressure measurement unit  130  may be configured in any manner as long as it can measure the pressure of the air (the fluid) in the tank unit  120 . The pressure measurement unit  130  may be provided at the tank unit  130  or may be provided in the tank unit  120 . 
     Microcomputer Unit  140   
     The microcomputer unit  140  contains an obtaining part  146 , an output part  144  and a storage part  142 . The obtaining part  146  obtains the value of the pressure of the air in the tank unit  120  based on the pressure value information inputted from the pressure measurement unit  130 . The obtaining part  146  is connected to the pressure measurement unit  130  and obtains the measured value of the pressure of the air in the tank unit  120  based on the pressure value information inputted from the pressure measurement unit  130 . The output part  144  has a function of outputting a drive frequency to the coils  50   a ,  50   b . The output part  144  outputs the drive frequency which is based on information on the value of the pressure of the air in the tank unit  120  obtained by the obtaining part  146  to the coils  50   a ,  50   b  of the pump  1 . 
     The microcomputer unit  140  has a function as a control unit and changes the vibration of the vibration actuator of the pump  1  based on the measured value of the pressure of the air in the tank unit  120 . The microcomputer unit  140  obtains the value of the pressure of the air in the tank unit  120 , which is the measured value of the pressure in the present embodiment, as the information on the value of the pressure and controls the drive frequency of the electrical current supplied to the coils  50   a ,  50   b  based on this obtained information on the value of the pressure. 
     The microcomputer unit  140  changes the frequency of the drive signal outputted to the pump  1  to change the pressure of the air in the tank unit  120 . The microcomputer unit  140  controls the drive frequency so that the electrical current having the resonance frequency of the vibrating body  30  which can be changed according to the pressure of the air in the tank unit  120  is supplied to the coils  50   a ,  50   b . 
     For example, the microcomputer unit  140  refers a look-up table stored in a built-in ROM which is used as the storage part  142  to control so as to store the air in the tank unit  120  so that the pressure of the air in the tank unit  120  becomes predetermined pressure. A table or the like in which the drive frequency is associated with the value of the pressure of the air in the tank unit  120  for switching the drive frequency according to the value of the pressure of the air in the tank unit  120  can be used as the look-up table. 
     The microcomputer unit  140  switches the drive frequency supplied to the coils  50   a ,  50   b  between a first drive frequency for maximizing the flow rate of the air (see “G 2 ” in  FIG.  14   ) from the pump  1  to the tank unit  120  and a second drive frequency for maximizing the pressure of the air (see “G 1 ” in  FIG.  14   ) in the tank unit  120 . 
     Further, the microcomputer unit  140  switches the drive frequency from the first drive frequency (see “H 1 ” in  FIG.  14   ) to the second drive frequency (see “H 2 ” in  FIG.  14   ) in a phase of increasing the pressure of the air in the tank unit  120 . In this regard, a value of the pressure at a timing of switching the drive frequency in the phase of increasing the pressure of the air in the tank unit  120  is referred to as a phase value for the purpose of convenience. With this configuration, it is possible to increase the pressure of the air in the tank unit  120  efficiently and shortly compared with a case where the pump  1  is controlled with the first drive frequency (see “H 1 ” in  FIG.  14   ). The microcomputer unit  140  controls each part according to programs stored in a ROM or the like. With this configuration, it is possible to supply the drive signal of the drive frequency which is changed based on the obtained pressure value information of the air in the tank unit  120  to the coils  50   a ,  50   b  to control the pump  1 , for example. 
     When the pump control system  100  of the present embodiment drives the vibrating body  30  of the resonance-type vibration actuator  10  of the pump  1 , the pump control system  100  changes the frequency of the drive signal for driving the vibrating body  30  based on the pressure in the tank unit  120  and supplies the drive signal of the frequency depending on the pressure of the air in the tank unit  120  to the coils  50   a ,  50   b  of the pump  1 . 
     Operation Principal of Pump  1  by Microcomputer Unit  140  (Control Unit) 
     The pump  1  needs to ensure a required flow rate of the delivered fluid (air) and a required amplitude of the delivered fluid (air pressure). 
     Generally, in a configuration in which a tank is connected to a resonance-type vibration actuator, it has been known that a phenomenon that a resonance frequency changes according to a change of air pressure in the tank occurs. 
     Each of  FIG.  13 A  and  FIG.  13 B  is a view showing an operation principle of the pump  1  of the pump control system  100 .  FIG.  13 A  is a schematic view showing a state that a discharge flow path of a pump is opened in the pump  1  like a state that the tank unit is not connected to a discharge port (corresponding to the discharge portion  86 ).  FIG.  13 B  is a schematic view showing a state that the discharge flow path of the pump is closed by attaching the tank to the discharge port of the pump. 
     In the state that the discharge flow path of the pump performing the resonant drive is opened (this state is also referred to as “a pump opened state”) as shown in  FIG.  13 A , when the pump vibrates, that is when the movable wall is displaced by the drive of the pump unit, the air discharged from the sealed chamber is discharged to the outside of the pump through the discharge port. In contrast, in the state that the tank unit (corresponding to the tank unit  120 ) is connected to the pump performing the resonant drive and the discharge flow path to the outside of the pump is closed (this state is also referred to as “a pump closed state”) as shown in  FIG.  13 B , the air in the tank unit influences the vibration of the pump. In this regard, this influence is caused by the configuration in which the sealed chamber and the tank unit are communicated with each other through the discharge port (corresponding to the discharge portion  86 ) so that the fluid can communicate therebetween. 
     Namely, when the pressure in the tank unit starts to increase, the air discharged from the pump  1  is directly supplied into the tank unit and thus the air exhibits behavior similar to that in the pump opened state. On the other hand, when the pressure in the tank unit increases, the air supplied from the pump  1  is stored in the tank unit (the flow of the air is indicated by a thick arrow line) because there is no escape portion for the air supplied from the pump  1 . 
     The air in the tank unit communicated with the sealed chamber so that the fluid can communicate therebetween influences the pump  1  (more specifically, the pump units  80  and the vibrating body  30 ) through the supplied air and serves as an air spring in the pump  1 . As described above, in the case that the tank unit is attached to the discharge port of the pump  1 , action of the air spring works in the pump closed state unlike the pump opened state. Thus, the resonance frequency f in the pump opened state expressed by the following equation (6) changes to a resonance frequency f′ in the pump closed state expressed by the following equation (7). Namely, when the pressure in the tank unit  120  increases due to the drive of the pump  1  in the pump closed state, a spring property also increases and thus the resonance frequency of the actuator of the pump is shifted to the higher side compared with the pump opened state. 
     
       
         
           
             
               
                 
                   Equation 
                   ⁢ 
                       
                   6 
                 
               
               
                  
               
             
             
               
                 
                   f 
                   = 
                   
                     
                       1 
                       
                         2 
                         ⁢ 
                         π 
                       
                     
                     ⁢ 
                     
                       
                         k 
                         J 
                       
                     
                   
                 
               
               
                 
                   ( 
                   6 
                   ) 
                 
               
             
           
         
       
     
     f: Resonance frequency in pump opened state [Hz] 
     k: Spring constant of actuator [Nm/rad] 
     J: Inertial moment [kg*m 2 ] 
     
       
         
           
             
               
                 
                   Equation 
                   ⁢ 
                       
                   7 
                 
               
               
                  
               
             
             
               
                 
                   
                     f 
                     ′ 
                   
                   = 
                   
                     
                       1 
                       
                         2 
                         ⁢ 
                         π 
                       
                     
                     ⁢ 
                     
                       
                         
                           k 
                           + 
                           
                             k 
                             air 
                           
                         
                         J 
                       
                     
                   
                 
               
               
                 
                   ( 
                   7 
                   ) 
                 
               
             
           
         
       
     
     f′: Resonance frequency in pump closed state 
     k air : Spring constant of air 
     With considering these matters, the pump control system  100  has frequency characteristics of the pressure of the air in the tank unit and the flow rate of the air from the tank unit shown in  FIG.  14   .  FIG.  14    is a view showing frequency characteristics of the pressure of the air in the tank unit in the pump opened state and the pump closed state when the resonance-type pump of the present embodiment is used. As shown in  FIG.  14   , a maximum value of pressure G 1  of the air in the tank unit in the pump closed state and a maximum value of pressure G 2  of the air into the tank unit which represents the flow rate of the air from the pump in the pump opened state into the tank unit (hereinafter, “G 2 ” is referred to as “a flow rate G 2 ” because “G 2 ” represents the flow rate of the air from the pump into the tank unit) of the resonance-type pump at each drive frequency are achieved by drive at different resonance frequency bands (the vicinities of resonance points H 1 , H 2 ). For example, in a case of a resonance-type pump performing resonant drive at a drive frequency H 1  (a first drive frequency H 1 ), the flow rate G 2  becomes large (becomes maximum in the drawing) in the pump opened state when the pump is driven at the drive frequency H 1  (the first drive frequency H 1 ). However, since the air acts with respect to the vibrating body  30  as the spring in the pump closed state, a resonance point of the vibrating body  30  of the pump is shifted (shifted to the resonance point H 2  in  FIG.  14   ) and thus it becomes difficult to increase the pressure G 1 . On the other hand, with considering the shift of the resonance point, when the pump is drive in the resonance state at a frequency (the second drive frequency H 2 ) in the vicinity of the drive frequency H 2  which is a frequency higher than the drive frequency H 1 , the pressure G 1  increases. However, the pump is driven at the resonance frequency at which it is difficult to increase the flow rate G 2 . As described above, in a device such as the example of sphygmomanometer for which predetermined pressure is required in the tank unit  120 , when the pump is driven in the resonance state with a single frequency, the pump needs to be driven at a frequency in which there is disadvantage for either one of the flow rate and the pressure. 
     In order to use these characteristics, the microcomputer unit  140  (the control unit) in the pump control system  100  of the present embodiment changes the drive frequency when the pressure in the tank unit  120  having a predetermined volume to a predetermined pressure value. Specifically, the microcomputer unit  140  changes the drive frequency by switching the drive frequency between the first drive frequency H 1  for maximizing the flow rate G 2  of the air from the pump  1  into the tank unit  120  and the second drive frequency H 2  for maximizing the pressure G 1  of the air in the tank unit  120 . 
       FIG.  15    is a view showing one example of a frequency control in the pump control system  100  according to the present embodiment of the present invention. 
     In the pump control system  100 , the microcomputer unit  140  controls so as to supply the air (the fluid) into the tank unit  120  to increase the pressure of the air in the tank unit  120  until the pressure of the air in the tank unit  120  reaches the predetermined pressure. 
     The predetermined pressure (value) is appropriately changed depending on an application target of the pump control device and the pump control system  100  of the present embodiment. In an exemplary case that the pump control system  100  (the pump control device) is applied to the sphygmomanometer, 18 kPa (135 mmHg) or more is defined as high-blood pressure according to high-blood pressure therapy guideline (JSH 2004) and JIS standard (T115) for a noninvasive mechanical sphygmomanometer defines that blood pressure should not exceed 40 kPa. The predetermined pressure (value) is set according to these definitions. The predetermined pressure value may be set to be 40 kPa and may be variable in the range of 18 kPa to 40 kPa. Hereinafter, description will be given to a case that a tank volume is constant (for example, 500 cc) and the pressure in the tank unit  120  is increased to 40 kPa by the pump control system  100  with reference to  FIG.  15   . 
     In this case, the microcomputer unit  140  supplies the drive signal of a frequency at which the increase of the pressure from zero is quick, that is the drive signal of a frequency at which an increase degree of the pressure from zero is high, to the coils  50   a ,  50   b . More specifically, the drive signal of lower one frequency (indicated by “H 1 ” as is the case of  FIG.  14   ) of the first drive frequency H 1  and the second drive frequency H 2 , that is the drive signal of the first drive frequency H 1  is inputted to the coils  50   a ,  50   b  to excite the coils  50   a ,  50   b.    
       FIG.  15    shows a relationship between the pressure and a pressure increase time due to the drive with the first drive frequency H 1  and the drive with the second drive frequency H 2  (&gt;H 1 ) (indicated by “H 2 ” as is the case of the frequency indicated by “H 2 ” in  FIG.  14   ). The microcomputer unit  140  switches a process with the first drive frequency H 1  to a process with the second drive frequency H 2  at a predetermined switching timing. This switching timing is changed based on a pressure state of the air in the tank unit  120 . A timing when a gradient indicating the increase of the pressure value of the air in the tank unit  120  becomes gradual is indicated by “frequency switching” in  FIG.  15   . The drive frequency is changed from the first drive frequency H 1  to the second drive frequency H 2  at this timing when the gradient becomes gradual. With this configuration, at a rise time (a starting time of the pump  1 ), the pump  1  is driven by the drive signal of the first drive frequency H 1  at which the increase of the pressure of the air in the tank unit  120  is quick. Further, at the timing (the “frequency switching” in  FIG.  15   ) when the gradient indicating the increase of the pressure of the air in the tank unit  120  with the drive signal of the first drive frequency H 1  becomes gradual, the drive frequency is changed from the first drive frequency H 1  to the second drive frequency H 2 . A characteristic obtained by shifting the drive frequency from the first drive frequency H 1  to the second drive frequency H 2  as described above is indicated by “K 1 ” in  FIG.  15   . 
     Specifically, different frequencies (for example, the first drive frequency H 1  and the second drive frequency H 2 ) are compared with each other and the coils  50   a ,  50   b  are excited with the first drive frequency H 1  at which the pressure increase time from the rising from zero to the reach to the pressure value at the timing of switching the drive frequency, that is the reach to the phase value (about 10 kPa) is short to allow the vibrating body  30  to vibrate in the resonance state. In the resonant drive with the first drive frequency H 1 , the pressure increase time of the air in the tank unit  120  is short until the pressure reaches about 10 kPa. However, if the resonant drive is continued with the first drive frequency H 1 , the pressure in the tank unit  120  does not increase to the predetermined pressure value (for example, 40 kPa). 
     Further, in a case of performing the resonant drive with the second drive frequency H 2  which is higher than the first drive frequency H 1 , it is possible to make the pressure of the air in the tank unit  120  higher than the predetermined high pressure (for example, 40 kPa), whereas the pressure increase time of the air in the tank unit  120  from zero to the phase value (about 10 kPa) is longer than that of the case of performing the resonant drive with the first drive frequency H 1 . Thus, in the present embodiment, the resonant drive of the pump  1  is started by the drive signal of the first drive frequency H 1  and then the drive frequency of the drive signal is changed to the second drive frequency H 2  at the predetermined switching timing (for example, the timing when the pressure reaches 10 kPa). With this configuration, it is possible to drive the pump  1  with the characteristic K 1  shown in  FIG.  15   . 
     With this configuration, it becomes possible to increase the pressure with a shorter time compared with the resonant drive with the single frequency (the second drive frequency H 2 ). Specifically, it is possible to achieve the predetermined high pressure (for example, 40 kPa) by utilizing a characteristic curve of the characteristic K 1  in  FIG.  15    with a shorter time compared with a case of utilizing a characteristic curve (indicated by a dotted line in  FIG.  15   ) of the case of performing the resonant drive with only the second drive frequency H 2 . 
       FIG.  16    is a view showing one example of a control flow of the pump according to the present embodiment of the present invention. As shown in  FIG.  16   , at first, the drive frequency of the drive signal of the pump control system  100  is set to a drive frequency  1  (the first drive frequency H 1 ) at a step S 11 . At a step S 12 , the microcomputer unit  140  uses the pressure measurement unit  130  to measure the pressure in the tank unit  120  and uses the obtaining part  146  to obtain the measured pressure as the pressure value of the air in the tank unit  120 . At a step S 13 , the microcomputer unit  140  determines whether or not the obtained pressure value of the air reaches a switching pressure value (the phase value) and repeats this determination until the obtained pressure value of the air reaches the switching pressure value. Namely, at the step S 13 , the drive frequency of the electrical current supplied to the coils  50   a ,  50   b  is switched between the first drive frequency H 1  for maximizing the flow rate G 2  of the air (the fluid) from the pump  1  into the tank unit  120  and the second drive frequency H 2  for maximizing the pressure G 1  of the air (the fluid) in the tank unit  120 . If the pressure value reaches the switching pressure value at the step S 13 , the process is shifted to a step S 14 . At the step S 14 , the drive frequency of the electrical current supplied to the coils  50   a ,  50   b  is set to a drive frequency  2  (the second drive frequency H 2 ). 
     Next, the microcomputer unit  140  measures the pressure of the air in the tank unit  120  (a step S 15 ) and then determines whether or not the measured pressure reaches required pressure, that is the predetermined pressure value (a step S 16 ). The microcomputer unit  140  repeats this determination until the measured pressure reaches the predetermined pressure value. 
     The present embodiment is different from, for example, a frequency response measurement using drive of each single frequency (a series of measurement processes from a process of driving the pump with each set drive frequency to a process of determining whether a current drive frequency is a required drive frequency when pressure caused by this drive is a maximum pressure value). Namely, according to the present embodiment, it is unnecessary to control so as to output maximum pressure at each set drive frequency and it is possible to prevent a control time from increasing unlike the frequency response measurement. According to the present embodiment, it is possible to downsize the pump and ensure more preferable pump pressure and flow rate, thereby stably driving the pump. In particular, in the pump using the resonance-type vibration actuator, it is possible to increase the pressure of the air in the tank unit  120  with a shorter time compared with the drive with the single frequency. 
     Second Embodiment 
       FIG.  17    is a block diagram showing a schematic configuration of a pump according to a second embodiment of the present invention. A pump control system  100 A shown in  FIG.  17    uses a timer  160  instead of the pressure detection unit  130  (see  FIG.  1   ) compared with the pump control system  100 . 
     Since a basic configuration of the pump control system  100 A according to the second embodiment is the same as the basic configuration of the pump control system  100  of the first embodiment, only different configurations will be described. The same configurations are respectively labelled with the same numbers and the same names and description for the same configurations will be omitted. 
     The pump control system  100 A contains the pump  1 , the tank unit  120 , a microcomputer unit  140 A and a timer  160 . 
     The timer  160  measures a drive time of the vibrating body  30  to obtain the drive time of the vibrating body  30  while the pressure of the air (the fluid) in the tank unit  120  is increased. The obtaining part  146  obtains the drive time of the vibrating body  30 . When the obtaining part  146  obtains the drive time of the vibrating body  30  from the timer  160 , the pressure value information is obtained from the drive time of the vibrating body  30 . This pressure value information in the present embodiment is a table indicating the drive time of the vibrating body  30  set in advance and the pressure of the air in the tank unit  120  which increases according to this drive time and stored in the storage part  142 . For example, this table is a timing table indicating a timing of switching the drive frequency of the electrical current supplied to the coils  50   a ,  50   b  in the phase of increasing the pressure of the air in the tank unit  120  from the first drive frequency H 1  to the second drive frequency H 2 . 
     The microcomputer unit  140 A uses the table stored in the storage part  142  to operate each part, in particular, control the drive frequency of the electrical current supplied to the coils  50   a ,  50   b  based on the table obtained by the obtaining part  146  as the pressure value information. As described above, in the pump control system  100 A, the microcomputer unit  140 A obtains the pressure increase time in which the pressure of the air in the tank unit  120  increases, that is the drive time of the vibrating body  30  with the timer  160  and obtains the pressure value information indicating a value corresponding to the pressure with the obtaining part  146  without measuring the pressure in the tank unit  120 . The microcomputer unit  140 A controls the drive frequency of the electrical current supplied to the coils  50   a ,  50   b  based on this obtained information. 
     With this configuration, the microcomputer unit  140 A can set a frequency switching time (timing) when the drive frequency of the electrical current supplied to the coils  50   a ,  50   b  is controlled and thus can perform the same operation as that of the microcomputer unit  140 . Description will be given to one example of the operation of the microcomputer unit  140 A with reference to  FIG.  15   . In  FIG.  15   , when the drive is performed with the first drive frequency H 1 , the pressure hardly increases at a phase that is a lapse of about 5 seconds (the position indicated by “the frequency switching” in  FIG.  15   ). A timing table indicating such a frequency switching position may be stored in the storage part  142  as the pressure value information. 
     The microcomputer unit  140 A performs the control of switching the drive frequency of the electrical current supplied to the coils  50   a ,  50   b  from the first drive frequency H 1  to the second drive frequency H 2  after 5 seconds from the start of the pressure increase based on the pressure value information stored in the storage part  142 , that is the timing table indicating the frequency switching position. With this configuration, as is the case of using the pressure value detected by the pressure detection unit  130 , the microcomputer unit  140 A can control the drive frequency of the electrical current supplied to the coils  50   a ,  50   b  so as to obtain the characteristic K 1  shifted from the first drive frequency H 1  to the second drive frequency H 2 . 
     Switching Pattern  1   
       FIG.  18    and  FIG.  19    are views showing patterns of a drive frequency control of the electrical current supplied to the coils  50   a ,  50   b  in cases that the tank volume is changed.  FIG.  20    shows a table in the case of switching the drive frequency based on the pressure value with the pump of the first embodiment.  FIG.  21 A  and  FIG.  21 B  show tables in the case of switching the drive frequency based on the time with the pump of the second embodiment. Although initial drive frequencies are 150 Hz, 250 Hz and 270 Hz respectively corresponding to different pressure and flow rates in each figure, these initial frequencies are merely one example. A high and low relationship among the initial drive frequencies is not limited thereto as long as the initial drive frequencies are different from each other. 
     Characteristics K 2 , K 3  shown in  FIG.  18    and  FIG.  19    are characteristics at the time of using a frequency in a “frequency band (area) in which the flow rate is easily increased” in the characteristic of the resonance-type actuator whose characteristics in the pump opened state and the pump closed state are different from each other (see  FIG.  14   ). 
     The pump control system  100  of the first embodiment uses the table shown in  FIG.  20    to perform the drive frequency control shown in  FIG.  18    and  FIG.  19    based on the pressure value in the tank unit  120  measured by the pressure measurement unit  130 . In  FIG.  18    and  FIG.  19   , when the drive frequency of the drive signal is controlled by the frequency shift so as to obtain the characteristics K 2 , K 3 , the drive frequency of the electrical current supplied to the coils  50   a ,  50   b  is changed twice to shorten the increase time of the pressure in the tank unit  120 . Both of the twice changes of the drive frequency are performed by switching the drive frequency of the electrical current supplied to the coils  50   a ,  50   b  between the drive frequency for maximizing the flow rate G 2  of the air and the drive frequency for maximizing the pressure G 1  of the air in the phase of increasing the pressure of the air in the tank unit  120 . 
     In  FIG.  20   , three different frequencies which are examples of the initial drive frequencies are associated with the pressure (“target pressure”) of the fluid in the tank unit  120  when each initial frequency is switched to these frequencies. With this configuration, the pump control system  100  can effectively increase the air in the tank unit  120  so as to correspond to the change of the pressure of the fluid in the tank unit  120  regardless of the tank volume more quickly than the case of performing the drive with the single frequency (see arrow lines indicating the shortening of the increase time in  FIG.  18    and  FIG.  19   ). 
     The microcomputer unit  140 A of the pump control system  100 A of the second embodiment uses the table shown in  FIG.  21 A  to perform the control so as to obtain the characteristic K 2  shown in  FIG.  18    and uses the table shown in  FIG.  21 B  to perform the control so as to obtain the characteristic K 3  shown in  FIG.  19   . Each of the tables in  FIG.  21 A  and  FIG.  21 B  contains a table in which a plurality of initial drive frequencies differing from each other, times in which the drive is performed by these initial drive frequencies, and the target pressure corresponding to the drive time are associated with each other. The tables are stored in the storage part  142 . With this configuration, the pump control system  100 A can use the tables depending on the tank volume to effectively increase the air in the tank unit  120  so as to correspond to the change of the pressure of the fluid in the tank unit  120  more quickly than the case of performing the drive with the single frequency. 
     Switching Pattern  2   
       FIG.  22    is a view showing a pattern of gently increasing the air in the tank according to the frequency control of the first embodiment and the second embodiment.  FIG.  23    shows a table for a case of controlling so as to obtain a characteristic K 4  by switching the drive frequency shown in  FIG.  22    based on the pressure value with the pump of the first embodiment. Further,  FIG.  24    shows a table for a case of controlling so as to obtain the characteristic K 4  by switching the drive frequency shown in  FIG.  22    based on the time with the pump of the second embodiment. Although initial drive frequencies are 300 Hz, 280 Hz and 270 Hz in each figure, these initial frequencies are merely one example. A high and low relationship among the initial drive frequencies is not limited thereto as long as the initial drive frequencies are different from each other. 
     The frequency control shown in  FIG.  22    uses a frequency in a “frequency band (area) in which the flow rate is hardly increased” which is a higher frequency area than the second drive frequency H 2  in the characteristic of the resonance-type actuator shown in  FIG.  14   . As described above, the pump control system for controlling the drive frequency of the electrical current supplied to the coils  50   a ,  50   b  is used for a case of extending the pressure increase time such as a case that it is desired to gently increase the pressure of the air. For example, the pump may be used in a case that it is required to gently deliver the air at the time of vascular testing of a baby and a toddler, fastening of a belt with respect to a subject being tested. 
     Third embodiment 
       FIG.  25    is a view schematically showing a pump control system according to a third embodiment of the present invention. A pump device shown in  FIG.  25    is, for example, a sphygmomanometer  10 D. The sphygmomanometer  10 D includes a cuff  102  corresponding to the tank unit  120 , a tube  5  for supplying air into the cuff  102 , a pump drive unit  101 , and a pressure measurement unit  13 D. 
     The drive unit  101  includes a resonance pump  1 D which is the pump  1  shown in  FIG.  1   , and a control unit  140  as the microcomputer unit. 
     The control unit  140  which is the microcomputer unit is connected to the resonance pump  1 D and the pressure measurement unit  13 D and supplies the drive signal to the resonance pump  1 D. 
     The resonance pump  1 D drives according to the drive signal from the microcomputer unit  140 . Specifically, the tube  5  is connected to the discharge portion  86  of the resonance pump  1 D and the vibrating body  30  vibrates in the resonance pump  1 D. Thus, the pump units are driven to suitably supply the air in the cuff of the sphygmomanometer or the like. According to the configuration of the pump control system, it is possible to downsize the pump and ensure the more preferable pump pressure and pump flow rate, thereby stably driving the pump. Further, regarding the cuff, it is possible to increase the pressure in the cuff to the predetermined pressure value in the short time. 
     The embodiments of the present invention have been explained in the above description. In this regard, the above description is provided to explain the examples of the preferred embodiments and the scope of the present invention is not limited thereto. Namely, the description for the configuration of the above-described device and the shape of each part is merely one example. Thus, it is apparent that various modifications and additions to these examples can be practiced within the scope of the present invention. 
     INDUSTRIAL APPLICABILITY 
     The pump according to the present invention can be downsized, makes it possible to ensure the more preferable pump pressure and pump flow rate, and has the effect of enabling the stable drive. For example, the pump of the present invention are useful for a wearable device to which a high output and a thin thickness are desired. For the reasons stated above, the present invention has industrial applicability.