Abstract:
Provided is an electromagnetic valve system for carrying out a compressed air supply to and evacuation from a plurality of air chambers of massage instruments of an air-type massage device, comprising: a plurality of first electromagnetic valves which are connected to each air chamber via supply tubes; a second electromagnetic valve further comprising a first aperture which communicates with external air; and a plurality of first check valves which are disposed within a header in an intermediate location between the second electromagnetic valve and each air chamber with a connection tube therebetween, and allow air to pass from the air chambers toward the second electromagnetic valve only when air pressure on the second electromagnetic valve side is lower than air pressure on the air chamber side.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to an electromagnetic valve system and also relates to a pneumatic massage apparatus having the electromagnetic valve system. 
       BACKGROUND ART 
       [0002]    There has heretofore been known a pneumatic massage apparatus having a plurality of air chambers to be fitted around an arm or a leg, in which each air chamber is inflated and deflated by supplying and discharging compressed air thereinto and therefrom, respectively, to thereby massage the body. Such a massage apparatus uses an electromagnetic valve system having a plurality of electromagnetic valves for supplying and discharging compressed air into and from the plurality of air chambers, respectively. 
         [0003]    Electromagnetic valves used in such an electromagnetic valve system are three-way valves switchable between a position where compressed air is supplied into air chambers of a massage device and a position where the compressed air in the air chambers is released to the atmosphere. Usually, the electromagnetic valves are configured as follows: When a solenoid of each electromagnetic valve is energized, a valve element is moved to a first position with electromagnetic force against urging force of a spring to supply compressed air into the associated air chamber. When the solenoid is not energized, the valve element is held in a second position by being urged with the spring to discharge the compressed air from the air chamber (Patent Literature 1). 
       PATENT LITERATURE 
       [0004]    Patent Literature 1: Japanese Patent No. 3909789 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0005]    Conventional pneumatic massage apparatuses of the type described above typically use an AC power supply. In view of convenience in use, however, it is desirable to use a battery as a power supply to provide a portable pneumatic massage apparatus. 
         [0006]    The present invention has been made in view of the above-described convenience in use, and it is an object of the present invention to provide a pneumatic massage apparatus usable even with a battery power supply and to provide an electromagnetic valve system suitable for use in the pneumatic massage apparatus. 
       Solution to Problem 
       [0007]    The present invention provides an electromagnetic valve system for supplying and discharging compressed air into and from a plurality of air chambers of a massage device of a pneumatic massage apparatus. The electromagnetic valve system includes: a compressed air inlet for receiving compressed air; a plurality of first electromagnetic valves to be connected to the air chambers, respectively, of the massage device, the first electromagnetic valves each having a first opening communicating with the compressed air inlet, a second opening communicating with an outside atmosphere, and a third opening for communicating with an associated one of the air chambers, and the first electromagnetic valves each being switchable between a first position where the second opening is closed and the first opening and the third opening are communicated with each other and a second position where the first opening is closed and the second opening and the third opening are communicated with each other; a second electromagnetic valve having a first opening communicating with the outside atmosphere and a second opening for communicating with the plurality of air chambers, the second electromagnetic valve being switchable between a first position where communication between the first opening and second opening of the second electromagnetic valve is cut off and a second position where the first opening and second opening of the second electromagnetic valve are communicated with each other; and a plurality of first check valves provided, respectively, between the air chambers and the second opening of the second electromagnetic valve, the first check valves allowing air to flow from the air chambers toward the second opening of the second electromagnetic valve only when the air pressure on the second opening side of the second electromagnetic valve is lower than the air pressure on the air chamber side. The first electromagnetic valves are self-holding electromagnetic valves that maintain either the first or second position assumed thereby when a supply voltage to the first electromagnetic valves drops below a given value even after the supply voltage to the first electromagnetic valves has dropped below the given value, and the second electromagnetic valve is an automatic release type electromagnetic valve that switches over to the second position when a supply voltage to the second electromagnetic valve drops below a given value. 
         [0008]    The first electromagnetic valves for supplying and discharging compressed air into and from the air chambers of the massage device are self-holding electromagnetic valves. Therefore, electric power is mainly consumed only at the moment when the position of the valve element is switched between the first position and the second position. Accordingly, the amount of electric power consumed by the electromagnetic valves can be reduced, and it becomes possible to use the pneumatic massage apparatus for a longer period of time with limited power supply capacity. On the other hand, the second electromagnetic valve is an automatic release type electromagnetic valve. Therefore, when the electric power supplied to the second electromagnetic valve is cut off or drops below a given value, the second electromagnetic valve switches over to the second position to release the compressed air in each air chamber to the atmosphere. Accordingly, it is also possible to ensure safety in emergency situations. 
         [0009]    Preferably, the electromagnetic valve system may further include a control device controlling the first and second electromagnetic valves. The control device controls the second electromagnetic valve such that the voltage supply to the second electromagnetic valve is stopped when the supply voltage to the second electromagnetic valve drops below a set value, thereby bringing the second electromagnetic valve to the second position. 
         [0010]    Specifically, the second electromagnetic valve may further have a third opening communicating with the compressed air inlet, so that, when the second electromagnetic valve is in the first position, the first opening of the second electromagnetic valve is closed, and the second opening and third opening of the second electromagnetic valve are communicated with each other, and when the second electromagnetic valve is in the second position, the third opening of the second electromagnetic valve is closed, and the first opening and second opening of the second electromagnetic valve are communicated with each other. 
         [0011]    In this case, the electromagnetic valve system may further include a second check valve provided between the compressed air inlet and the third opening of the second electromagnetic valve, the second check valve allowing air to flow only in a direction from the compressed air inlet toward the third opening of the second electromagnetic valve. 
         [0012]    Alternatively, the electromagnetic valve system may be arranged such that the second opening of the second electromagnetic valve also communicates with the compressed air inlet, and that the second electromagnetic valve is configured to close the second opening when the second electromagnetic valve is in the first position, and to open the second opening so as to communicate the first opening and the second opening with each other when the second electromagnetic valve is in the second position. 
         [0013]    In this case, the electromagnetic valve system may further include a second check valve provided between the compressed air inlet and the second opening of the second electromagnetic valve and hence between the compressed air inlet and the air chambers, the second check valve allowing air to flow only in a direction from the compressed air inlet toward the second opening of the second electromagnetic valve and the air chambers. 
         [0014]    Even when the pressure on the compressed air inlet side drops, the air on the second electromagnetic valve side is prevented from flowing backward, which would otherwise cause a drop in pressure on the second electromagnetic valve side. Therefore, when the air pressure on the second opening side of the second electromagnetic valve becomes lower than the air pressure on the air chamber side, the first electromagnetic valves are prevented from opening unnecessarily. 
         [0015]    More preferably, the electromagnetic valve system may further include a third check valve provided between the compressed air inlet and the first opening of each of the first electromagnetic valves, the third check valve allowing air to flow only in a direction from the compressed air inlet toward the first opening. 
         [0016]    Preventing air from flowing out toward the compressed air inlet makes it possible to reduce or stop the output of a compressed air supply device, which is connected to the compressed air inlet, when it is unnecessary to supply new compressed air into any of the air chambers, and it is therefore possible to further reduce the power consumption. 
         [0017]    Preferably, the supply voltage may be supplied by a battery. 
         [0018]    Specifically, the first electromagnetic valves may each have: a solenoid coil; a plunger magnetically attracted to the solenoid coil; a valve element attached to the distal end of the plunger to selectively close the first opening and second opening of the first electromagnetic valve; a spring urging the plunger in a direction opposite to a direction in which the plunger is attracted to the solenoid coil; and a permanent magnet magnetically attracting the plunger to maintain the position of the plunger. By applying a forward voltage to the solenoid coil to generate a magnetic force that increases magnetic attraction action of the permanent magnet, the plunger is attracted against urging force of the spring to bring the first electromagnetic valve to the first position. By applying a reverse voltage to the solenoid coil to generate a magnetic force that reduces the magnetic attraction action of the permanent magnet, the plunger is moved by the urging force of the spring to bring the first electromagnetic valve to the second position. 
         [0019]    With the above-described structure of the first electromagnetic valves, the solenoid coil is excited only at the moment when the valve element is to be moved between the first position and the second position. While the valve element is being held in the first or second position, the position of the valve element is maintained by the permanent magnet or the spring; therefore, it is unnecessary to excite the solenoid coil. Thus, no electric power is consumed while the valve element is being held in either of the first and second positions, and the period of time that electric power supply is needed becomes very short. Accordingly, the power consumption can be further reduced. 
         [0020]    In addition, the present invention provides a pneumatic massage apparatus including: a massage device fittable to one&#39;s body, the massage device having a plurality of air chambers that are inflated and deflated by supplying and discharging compressed air thereinto and therefrom, respectively, to thereby act on the body; a compressed air supply device prepared separately from the massage device; and any of the above-described electromagnetic valve systems, wherein the compressed air inlet is connected to the compressed air supply device, and the third opening of each of the first electromagnetic valves is connected to an associated one of the air chambers. When the supply voltage to the second electromagnetic valve drops below a given value, the second electromagnetic valve switches over to the second position to allow air in any of the air chambers that is in an inflated state to be released to the atmosphere through the first opening of the second electromagnetic valve. 
         [0021]    Embodiments of the present invention will be explained below based on the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0022]      FIG. 1  is an illustration of a pneumatic massage apparatus in which is used an electromagnetic valve system according to the present invention. 
           [0023]      FIG. 2  is a perspective view of an electromagnetic valve system according to a first embodiment of the present invention. 
           [0024]      FIG. 3  is a perspective view showing the interior of a header of the electromagnetic valve system shown in  FIG. 2 . 
           [0025]      FIG. 4  is a sectional view of a first electromagnetic valve of the electromagnetic valve system shown in  FIG. 2  when the first electromagnetic valve is in a first position. 
           [0026]      FIG. 5  is a sectional view of the first electromagnetic valve of the electromagnetic valve system shown in  FIG. 2  when the first electromagnetic valve is in a second position. 
           [0027]      FIG. 6  is a sectional view of a second electromagnetic valve of the electromagnetic valve system shown in  FIG. 2  when the second electromagnetic valve is in a first position. 
           [0028]      FIG. 7  is a sectional view of the second electromagnetic valve of the electromagnetic valve system shown in  FIG. 2  when the second electromagnetic valve is in a second position. 
           [0029]      FIG. 8  is a perspective view of an electromagnetic valve system according to a second embodiment of the present invention. 
           [0030]      FIG. 9  is a sectional view of a second electromagnetic valve of the electromagnetic valve system shown in  FIG. 8  when the second electromagnetic valve is in a first position. 
           [0031]      FIG. 10  is a sectional view of the second electromagnetic valve of the electromagnetic valve system shown in  FIG. 8  when the second electromagnetic valve is in a second position. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0032]    A massage apparatus  1  shown in  FIG. 1  has massage devices  2  to be fitted around legs, respectively. Each massage device  2  has a plurality of air chambers  3  disposed in series in the longitudinal direction thereof. The massage apparatus  1  further has a compressed air control unit  4  for supplying and discharging compressed air into and from each of the air chambers  3 . The air chambers  3  of the massage devices  2  are connected to the compressed air control unit  4  through a plurality of tubes  5 , respectively, for supplying and discharging compressed air. 
         [0033]    The compressed air control unit  4  has a compressed air supply device (not shown), e.g. an air pump, accommodated in a housing, an electromagnetic valve system  10  according to a first embodiment of the present invention, which is connected to the compressed air supply device, and a battery (not shown) for supplying electric power to the compressed air supply device and the electromagnetic valve system  10 . The electromagnetic valve system  10  has, as shown in  FIG. 2 , a header  20  having a compressed air inlet  22  connected to the compressed air supply device, a plurality of first electromagnetic valves  30  connected to the air chambers  3  through the tubes  5 , respectively, and a second electromagnetic valve  40  communicated with the header  20 . 
         [0034]    As will be understood from  FIG. 3 , which shows the electromagnetic valve system  10  with a header cap  21  removed therefrom, the header  20  has an upper chamber  26  and a lower chamber  27 . As shown in  FIGS. 3 ,  6  and  7 , the lower chamber  27  is communicated with the compressed air inlet  22  and also communicated with the upper chamber  26  through the second electromagnetic valve  40 . 
         [0035]    As shown in  FIGS. 4 and 5 , the lower chamber  27  is connected to the first electromagnetic valves  30  through respective check valves  53  (corresponding to a third check valve in the appended claims) that allow the compressed air supplied from the compressed air inlet  22  to be discharged from the lower chamber  27 . The upper chamber  26  is communicated with supply pipes  60  through a plurality of duckbill check valves  51  (corresponding to a first check valve in the appended claims), respectively. The check valves  51  block the flow of air from the supply pipes  60  toward the upper chamber  26  when the pressure of compressed air from the compressed air inlet  22  is applied to the upper chamber  26  through the second electromagnetic valve  40 . 
         [0036]    The first electromagnetic valves  30  each have a solenoid coil  31 , a plunger  32  provided in the solenoid coil  31  to extend in the longitudinal direction of the solenoid coil  31 , an annular-shaped permanent magnet  33  provided around the plunger  32  adjacently to the solenoid coil  31 , a housing  38  accommodating the solenoid coil  31 , the permanent magnet  33 , and the plunger  32 , a spherical valve element  35  secured to the distal end of the plunger  32  through a valve element support member  34 , and a spring  36  urging the plunger  32  rightward as seen in the figures. Each first electromagnetic valve  30  is a three-way valve having a first opening  37 - 1  communicating with the lower chamber  27  of the header  20 , a second opening  37 - 2  open to the atmosphere, and a third opening  37 - 3  connected to the associated supply pipe  60 . The three-way valve is configured to switch communication between the three openings with the spherical valve element  35 . The first electromagnetic valve  30  is driven between a first position shown in  FIG. 4  and a second position shown in  FIG. 5 . To bring the first electromagnetic valve  30  to the first position, a forward voltage is applied to the solenoid coil  31  to generate a magnetic field producing lines of magnetic force in the same direction as the direction of lines of magnetic force generated by the magnetic field of the permanent magnet  33 , which pass through the plunger  32 . Consequently, the magnetic flux density of the lines of magnetic force passing through the plunger  32  increases, thus causing the plunger  32  to be attracted leftward as seen in the figures against the urging force of the spring  36 . The housing  38  is formed from a magnetic material to form a magnetic circuit of the permanent magnet  33 . The magnetic reluctance of the magnetic circuit is reduced by the plunger  32  brought to the first position shown in  FIG. 4  because the plunger  32  is close to an end wall  38   a  of the housing  38 . Accordingly, even after the application of the forward voltage to the solenoid coil  31  has been stopped, the plunger  32  is held in the first position by the magnetic attraction action of the permanent magnet  33  against the urging force of the spring  36 . To switch the first electromagnetic valve  30  from the first position to the second position, a reverse voltage is applied to the solenoid coil  31  to generate a magnetic field that weakens the magnetic attraction action of the permanent magnet  33 , thereby allowing the plunger  32  to be pushed out rightward from the housing  38  by the urging force of the spring  36 . As the plunger  32  is pushed out from the housing  38 , the plunger  32  is brought away from the end wall  38   a  of the housing  38 , and the magnetic reluctance of the above-described magnetic circuit increases. Accordingly, the magnetic attraction action of the permanent magnet  33  decreases. Therefore, the plunger  32  is held in the second position by the urging force of the spring  36  even after the application of the reverse voltage to the solenoid coil  31  has been stopped. The first electromagnetic valve  30  is a self-holding electromagnetic valve that needs to apply a voltage to the solenoid coil  31  only when the plunger  32  is to be switched between the first and second positions and that need not apply a voltage to the solenoid coil  31  when the plunger  32  is hold in either the first or second position. Accordingly, the period of time that electric power is supplied to the first electromagnetic valves  30  during the operation of the massage apparatus  1  becomes very short; therefore, the power consumption is reduced. The housing  38 , which accommodates the solenoid coil  31  and so forth, is provided therein with a shock absorption member  39  for receiving the plunger  32  as attracted by the solenoid coil  31  to reduce impact noise when the plunger  32  is attracted. To increase the magnetic attraction action of the permanent magnet  33  when the first electromagnetic valve  30  is brought to the first position shown in  FIG. 4 , it is preferable for the shock absorption member  39  to have magnetic properties. 
         [0037]    When the first electromagnetic valve  30  is in the first position shown in  FIG. 4 , the second opening  37 - 2  is closed by the spherical valve element  35 , and the first opening  37 - 1  and the third opening  37 - 3  are communicated with each other. Consequently, compressed air supplied from the compressed air inlet  22  is supplied into the associated air chamber  3  through the check valve  53  and through the first and third openings  37 - 1  and  37 - 3  of the first electromagnetic valve  30 , causing the air chamber  3  to be inflated. When the first electromagnetic valve  30  is in the second position shown in  FIG. 5 , the first opening  37 - 1  of the first electromagnetic valve  30  is closed by the spherical valve element  35 , and the third opening  37 - 3  and the second opening  37 - 2  are communicated with each other. Consequently, compressed air in the associated air chamber  3  is discharged into the atmosphere through the second opening  37 - 2 , and thus the air chamber  3  deflates. The pneumatic massage apparatus  1  is configured to perform a desired massaging operation by controlling the first electromagnetic valve  30  connected to each air chamber  3  between the first position and the second position through a control device (not shown). 
         [0038]    The second electromagnetic valve  40  is, as shown in  FIGS. 6 and 7 , provided with a solenoid coil  41  disposed in a coil housing  48 , a shaft  42  extending through the solenoid coil  41 , a plunger  43  secured around the shaft  42  inside the solenoid coil  41 , a plunger receiving member  49  secured to the coil housing  48  at the left side of the plunger  43  inside the solenoid coil  41 , a first valve element  44 - 1  secured to one end of the shaft  42 , a second valve element  44 - 2  secured to the other end of the shaft  42 , and a spring  45  urging the shaft  42 , the plunger  43  and the first and second valve elements  44 - 1  and  44 - 2  rightward as seen in the figures. A valve housing  46  accommodating the solenoid coil  41  and so forth is provided with a first opening  47 - 1  open to the outside, a second opening  47 - 2  connected to the upper chamber  26  of the header  20  through a connecting pipe  62 , and a third opening  47 - 3  communicated with the lower chamber  27  through a duckbill check valve  52  (corresponding to a second check valve in the appended claims). When the solenoid coil  41  is supplied with electric power and thus excited, the plunger  43  is, as shown in  FIG. 6 , attracted leftward as seen in the figure against the urging force of the spring  45 . When the second electromagnetic valve  40  is in this first position, the first opening  47 - 1  of the second electromagnetic valve  40  is closed by the second valve element  44 - 2 , and the third opening  47 - 3  is open. Consequently, compressed air supplied from the compressed air inlet  22  is supplied from the lower chamber  27  into the upper chamber  26  of the header  20  through the check valve  52  and through the third opening  47 - 3  and the second opening  47 - 2 . When the electric power supplied to the second electromagnetic valve  40  drops below a given value, the magnetic force of the solenoid coil  41  of the second electromagnetic valve  40  that has been attracting the plunger  43  weakens, so that the plunger  43  is, as shown in  FIG. 7 , moved rightward as seen in the figure by the urging force of the spring  45 , thereby bringing the second electromagnetic valve  40  to a second position. When the second electromagnetic valve  40  is in the second position, the third opening  47 - 3  is closed by the first valve element  44 - 1 , and the first opening  47 - 1  is open. Accordingly, the compressed air in the upper chamber  26  of the header  20  is discharged, and the pressure in the upper chamber  26  reduces. Consequently, the duckbill check valves  51  ( FIGS. 4 and 5 ) open, and the compressed air in the air chambers  3  enters the upper chamber  26  through the tubes  5  and the supply pipes  60  and further passes through the connecting pipe  62  and through the second electromagnetic valve  40  from the second opening  47 - 2  to the first opening  47 - 1  before being discharged into the atmosphere. Thus, when the electric power supplied to the second electromagnetic valve  40  drops below a given value, compressed air remaining in the air chambers  3  of the massage devices  2  is discharged to deflate the air chambers  3 , thereby eliminating pressure to the user of the massage devices  2  to bring the massage apparatus to a safe condition. It should be noted that, in this specification, an electromagnetic valve that automatically shifts to the second position when the supply of electric power is stopped, as in the case of the second electromagnetic valve  40 , is referred to as an “automatic release type electromagnetic valve”. 
         [0039]    It should be noted that the arrangement may be as follows: The control device, which controls each electromagnetic valve, monitors the voltage of a battery used as a power supply of the massage apparatus, and while doing so, the control device stops the voltage supply to the second electromagnetic valve  40  to shift the valve  40  to the second position when the voltage supplied to the second electromagnetic valve  40  becomes lower than a certain set value, thereby discharging compressed air from the air chambers  3  to stop the massage apparatus in a safe condition. 
         [0040]    The following is an explanation of a basic operation of the massage apparatus  1  shown in  FIG. 1 . Before the massage apparatus  1  is started, the first electromagnetic valves  30  and the second electromagnetic valve  40  are in their respective second positions ( FIGS. 5 and 7 ). When the power supply is turned on, the second electromagnetic valve  40  assumes the first position ( FIG. 6 ), so that compressed air is supplied into the electromagnetic valve system  10  from the compressed air supply device through the compressed air inlet  22 . The supplied compressed air passes through the check valve  52  and further through the third and second openings  47 - 3  and  47 - 2  of the second electromagnetic valve  40  to reach the upper chamber  26 . This causes an increase in pressure in the upper chamber  26 . Consequently, the check valves  51  are closed to block air from flowing into the upper chamber  26  from the supply pipe  60  side. To inflate an air chamber  3 , the associated first electromagnetic valve  30  is driven to the first position ( FIG. 4 ). Consequently, compressed air passes from the lower chamber  27  through the check valve  53  and further through the first and third openings  37 - 1  and  37 - 3  of the first electromagnetic valve  30  and further passes through the supply pipe  60  and the tube  5  before being supplied into the associated air chamber  3 , thus causing the air chamber  3  to inflate. At this time, the pressure in the lower chamber  27  decreases momentarily. However, the pressure in the upper chamber  26  does not decrease because backflow of air from the upper chamber  26  to the lower chamber  27  is blocked by the check valve  52  ( FIG. 6 ). Accordingly, the check valve  51  that is closed by the pressure in the upper chamber  26  can maintain the closed state. That is, the air in the air chamber  3  having already been inflated is prevented from accidentally exiting through the check valve  51 . When the first electromagnetic valve  30  is returned to the second position ( FIG. 5 ), the air in the air chamber  3  is discharged through the second opening  37 - 2  of the first electromagnetic valve  30 , and consequently the air chamber  3  deflates. To stop the massage apparatus  1 , all the first electromagnetic valves  30  are returned to the second position to release the compressed air in all the air chambers  3  to the atmosphere from the second openings  37 - 2  of the first electromagnetic valves  30 . The compressed air supply device is stopped, and the second electromagnetic valve  40  is also returned to the second position ( FIG. 7 ) to release the air in the upper chamber  26  to the atmosphere through the second electromagnetic valve  40 . In this way, the massage apparatus  1  is stopped in a safe condition in which no compressed air is left therein. It should be noted that, when the massage apparatus  1  is to be stopped, the second electromagnetic valve  40  may be returned to the second position before the first electromagnetic valves  30  are done to discharge the air in the air chambers  3  from the first opening  47 - 1  of the second electromagnetic valve  40  through the check valves  51 . 
         [0041]      FIG. 8  shows an electromagnetic valve system  110  according to a second embodiment of the present invention. The electromagnetic valve system  110  has substantially the same structure as that of the electromagnetic valve system  10  according to the first embodiment. The constituent elements of the electromagnetic valve system  110  are denoted by reference numerals in  100  series, and the two lower digits of the reference numerals are the same as the reference numerals of the corresponding constituent elements in the first embodiment. The electromagnetic valve system  110  according to the second embodiment differs from the electromagnetic valve system  10  according to the first embodiment mainly in the second electromagnetic valve  140 . The second electromagnetic valve  140  has, as shown in  FIGS. 9 and 10 , a solenoid coil  141  disposed in a coil housing  148 , a shaft  142  extending through the solenoid coil  141 , a plunger  143  secured around the shaft  142  inside the solenoid coil  141 , a plunger receiving member  149  secured to the coil housing  148  at the right side of the plunger  143  inside the solenoid coil  141 , a valve element  144  secured to one end of the shaft  142  in a valve housing  146  connected to the right end (as seen in the figures) of the coil housing  148 , and a spring  145  urging the valve element  144  leftward as seen in the figures. The second electromagnetic valve  140  further has a first opening  147 - 1  formed as a gap between the valve housing  146  and the coil housing  148  and a second opening  147 - 2  opened on the right end wall of the valve housing  146  so as to communicate with an upper chamber  126  through a connecting pipe  162 . The second opening  147 - 2  also communicates with a lower chamber  127  of a header  120  through a duckbill check valve  152 , and thus the upper chamber  126  and the lower chamber  127  are communicated with each other through the check valve  152 , without through the second electromagnetic valve  140 . When the solenoid coil  141  is supplied with electric power and thus excited, as shown in  FIG. 9 , the plunger  143  is attracted, against the urging force of the spring  145 , rightward as seen in the figure to a position where the plunger  143  abuts against the plunger receiving member  149 . When the second electromagnetic valve  140  is in this first position, the second opening  147 - 2  thereof is closed. When the voltage supplied to the second electromagnetic valve  140  drops below a given value, the magnetic force of the solenoid coil  141  of the second electromagnetic valve  140  that has been attracting the plunger  143  weakens, so that the plunger  143  is, as shown in  FIG. 10 , moved leftward as seen in the figure by the urging force of the spring  145 , thereby bringing the second electromagnetic valve  140  to a second position. When the second electromagnetic valve  140  is in the second position, the second opening  147 - 2  is open and in communication with the first opening  147 - 1 . Accordingly, the compressed air in the upper chamber  126  of the header  120  is discharged, and the pressure in the upper chamber  126  reduces. Consequently, the duckbill check valves  51  ( FIG. 4 ) open, and the compressed air in the air chambers  3  is discharged into the atmosphere through the second and first openings  147 - 2  and  147 - 1  of the second electromagnetic valve  140 . 
         [0042]    The header  120  according to this embodiment has, as shown in  FIG. 8 , a multiplicity of fins  128  formed on the outer surface thereof to efficiently dissipate heat from the header  120  heated by compressed air. 
         [0043]    Although the electromagnetic valve systems  10  and  110  according to the above-described embodiments each have five first electromagnetic valves  30 , the number of first electromagnetic valves  30  may be varied according to need. For example, eight first electromagnetic valves  30  may be provided in correspondence to the massage devices  2  shown in  FIG. 1 . Further, it is not always necessary to use all the first electromagnetic valves  30  provided. If the number of air chambers  3  of the massage devices  2  is smaller than the number of first electromagnetic valves  30 , the excess first electromagnetic valves  30  may be held in the second position so as not to be used. 
         [0044]    The electromagnetic valve system  10  uses self-holding electromagnetic valves and is therefore capable of reducing the overall power consumption, even though it is necessary to use another electromagnetic valve of the automatic release type. Accordingly, the advantages of the present invention are effectively offered particularly when the electromagnetic valve system is driven by a battery as in the case of the electromagnetic valve system  10  according to the embodiment of the present invention. However, it is needless to say that the electromagnetic valve system may be driven by a power supply other than batteries, e.g. an AC power supply. 
         [0000]    
       
         
               
             
               
               
             
               
               
               
             
               
               
             
               
               
             
               
               
             
               
               
               
             
               
               
             
               
               
             
               
               
             
               
             
               
               
             
           
               
                   
               
               
                 List of Reference Signs: 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 1: massage apparatus 
                 2: massage device 
               
               
                 3: air chamber 
                 10: electromagnetic valve system 
               
               
                 20: header 
                 21: header cap 
               
               
                 22: compressed air inlet 
                 26: upper chamber 
               
               
                 27: lower chamber 
                 30: first electromagnetic valve 
               
               
                 31: solenoid coil 
                 32: plunger 
               
               
                 33: permanent magnet 
                 34: valve element support member 
               
               
                 35: valve element 
                 36: spring 
               
               
                 37-1: first opening (of first 
                 37-2: second opening (of first 
               
             
          
           
               
                   
                 electromagnetic valve) 
                 electromagnetic valve) 
               
             
          
           
               
                 37-3: third opening (of first 
                 38: housing 
               
             
          
           
               
                   
                 electromagnetic valve) 
               
             
          
           
               
                 38a: end wall 
                 39: shock absorption member 
               
               
                 40: second electromagnetic valve 
                 41: solenoid coil 
               
               
                 42: shaft 
                 43: plunger 
               
               
                 44-1: first valve element 
                 44-2: second valve element 
               
               
                 45: spring 
                 46: valve housing 
               
               
                 47-1: first opening (of second 
                 47-2: second opening (of second 
               
             
          
           
               
                   
                 electromagnetic valve) 
                 electromagnetic valve) 
               
             
          
           
               
                 47-3: third opening (of second 
                 48: coil housing 
               
             
          
           
               
                   
                 electromagnetic valve) 
               
             
          
           
               
                 49: plunger receiving member 
                 51: (first) check valve 
               
               
                 52: (second) check valve 
                 53: (third) check valve 
               
               
                 60: supply pipe 
                 62: connecting pipe 
               
               
                 110: electromagnetic valve system 
                  120: header 
               
               
                 126: upper chamber 
                  127: lower chamber 
               
               
                 128: fin 
                   140: second electromagnetic 
               
               
                   
                   valve 
               
               
                 141: solenoid coil 
                   142: shaft 
               
               
                 143: plunger 
                   144: valve element 
               
               
                 145: spring 
                   146: valve housing 
               
             
          
           
               
                 147-1: first opening (of second electromagnetic valve) 
               
               
                 147-2: second opening (of second electromagnetic valve) 
               
             
          
           
               
                 148: coil housing 
                   149: plunger receiving member 
               
               
                 162: connecting pipe