Patent Publication Number: US-2011048553-A1

Title: Pressure regulator

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a pressure regulator where the pressure of pressurized fluid such as gas or liquid is reduced to a predetermined secondary pressure from a primary pressure by way of a pressure control mechanism, and particularly to such a pressure regulator in which the pressure control mechanism includes a diaphragm. 
     2. Description of the Related Art 
     As disclosed in  FIG. 1  of Japanese Unexamined Patent Publication No. 2004-318683, there has been a pressure regulator provided with a diaphragm and a governor mechanism (pressure control mechanism) having a pressure control valve interlocked therewith. The governor mechanism of the pressure regulator has a supporter formed with a flange mounted on the diaphragm. The supporter is urged with a predetermined force by a pressure control spring to control the pressure control valve interlocked with the diaphragm at a predetermined pressure. The pressure control valve is positioned in the passage of the pressurized fluid and the pressure of the fluid downstream of the pressure control valve, that is, the secondary pressure, is controlled to be lower than the pressure of the fluid supplied from upstream of the pressure control valve, that is, the primary pressure. 
     As a technique of the prior art, there has been known, as disclosed in  FIG. 1  of Japanese Unexamined Patent Publication No. 8 (1996)-303773, a governor mechanism employed in a cassette-type gas cylinder used in a gas appliance. This governor mechanism is for leading the gas in a gas cylinder to a burner under a controlled pressure and provided with a regulation chamber parted with a diaphragm in the casing of the governor mechanism and a valve (a pressure control valve) open/close lever interlocked with the diaphragm in the regulation chamber. A mechanism for protecting the pressure regulator and for preventing the gas cylinder from exploding when the pressure in the gas cylinder is excessively high due to heat applied to the gas cylinder is provided in the governor mechanism and the gas cylinder. When the pressure in the gas cylinder is increased to an excessively high pressure, the mechanism causes the pressure in the gas cylinder to act on a safety valve in the governor mechanism to urge the safety valve to the retracted position. In response to refraction of the safety valve, a stem of the gas cylinder which has been abutted against the safety valve stretches to close an off valve interlocked with the stem to cut the gas supply to the governor mechanism from the gas cylinder. 
     In the pressure regulator disclosed in  FIG. 1  of Japanese Unexamined Patent Publication No. 2004-318683, the pressurized fluid supplied from the pressurized fluid supplying system, the flow rate of the pressurized fluid passing through the pressure control valve is controlled to control the pressure of the fluid by displacing the pressure control valve between the high pressure and the low pressure. However, the fluid pressure on the high pressure side of the pressure control valve is sometimes excessively raised from a predetermined temperature for some reasons including an increase in the environmental temperature or collapse of the container accommodating the pressurized fluid. When the pressure regulator is operated in this state, there is a fear that the pressure control valve which controls the amount of the pressurized fluid flowing into the low pressure side from the high pressure side and the diaphragm interlocked with the pressure control valve are excessively displaced to deform the pressure control valve to be unrestorable. In this case, the pressure control valve comes not to adequately function. 
     Further, in the pressure regulator disclosed in  FIG. 1  of Japanese Unexamined Patent Publication No. 8 (1996)-303773, a complicated mechanism is required for protecting the gas appliance against an excessively high gas pressure to be supplied, and an excessively high gas pressure cannot be dealt with unless association with the gas cylinder, not only the gas appliance. 
     SUMMARY OF THE INVENTION 
     In view of the foregoing observations and description, the primary object of the present invention is to provide a pressure regulator which is relatively simple in structure and high in reliability where the pressure control mechanism cannot be damaged even by an excessively high primary fluid pressure. 
     Another object of the present invention is to provide a pressure regulator which can protect the pressure control mechanism by a single pressure regulator. 
     In accordance with the present invention, there is provided a pressure regulator comprising 
     a housing having an inlet port through which pressurized fluid at a primary pressure is supplied, and a discharge port through which pressurized fluid at a secondary pressure lower than the primary pressure is discharged, and at the same time having a flow passage formed therein to extend from the inlet port to the discharge port, and 
     a pressure control mechanism which is disposed on the flow passage to reduce the primary pressure to the secondary pressure, where the improvement comprises that 
     the pressure control mechanism comprises a movable body including a diaphragm which is displaced in response to change in the pressure of the fluid and 
     the movable body is provided with an abutment portion which is brought into abutment against a part of the housing to prevent the movable body from being excessively displaced when the primary pressure becomes excessively high. 
     The movable body may be provided with a pair of members which are associated with each other from a first surface facing the flow passage of the diaphragm and from a second surface opposite to the first surface to support therebetween the diaphragm and the abutment portion may be formed in the portion projecting toward the second surface of the movable body. 
     The housing may be formed with a stopper portion comprising a projection opposed to the abutment portion. 
     The abutment portion may be a projection opposite to the inner surface of the housing. 
     According to the pressure regulator of the present invention, the pressure control mechanism which reduces the primary pressure to the secondary pressure has a movable body including a diaphragm which is displaced in response to change in the pressure of the fluid and the movable body is provided with an abutment portion which is brought into abutment against a part of the housing to prevent the movable body from being excessively displaced when the primary pressure becomes excessively high. Accordingly, the pressure regulator of the present invention exhibits the following result. When the movable body of the pressure control mechanism tends to be excessively displaced by an excessively high primary pressure, the movable body abuts against a part of the housing and an excessive displacement of the movable body is prevented, whereby the pressure control mechanism is prevented from being deformed to be unrestorable and/or being damaged and a pressure regulator which is simple in structure and high in reliability can be obtained. Further, a function of protecting a pressure regulator against an excessively high pressure can be realized by a pressure regulator by itself. 
     When the movable body is provided with a pair of members which are associated with each other from a first surface facing the flow passage of the diaphragm and from a second surface opposite to the first surface to support therebetween the diaphragm and the abutment portion is formed in the portion projecting toward the second surface of the movable body, the abutment portion can be formed on the movable body with simple structure. 
     Further, when the housing is formed with a stopper portion comprising a projection opposed to the abutment portion, the stopper portion can be formed with simple structure, and at the same time, since formation of the projection contributes to increase in the rigidity of the housing, a pressure regulator which is high in reliability can be obtained. 
     When the abutment portion is in the form of a projection opposite to the inner surface of the housing, the abutment portion can be formed with simple structure, and at the same time, since, a rigidity is given to the abutment portion, the movable body is less apt to be broken and a pressure regulator which is high in reliability can be obtained. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded perspective view showing a pressure regulator in accordance with a first embodiment of the present invention cut along a circumference around a shaft passing through the center thereof by a range of about 90 degrees, 
         FIG. 2  is a fragmentary enlarged view of  FIG. 1 , 
         FIG. 3  is a fragmentary enlarged view showing a lower part of the pressure regulator of  FIG. 1  cut along a circumference around a shaft passing through the center thereof by a range of about 90 Åã, 
         FIG. 4A  is a cross-sectional view showing the normal state of the pressure regulator of  FIG. 1  connected thereto a pressure vessel, 
         FIG. 4B  is a view similar to  FIG. 4A  showing a state of the pressure regulator where the pressure therein is increased excessively high, 
         FIG. 5  is an enlarged view of a part V surrounded by a chained line in  FIG. 4B  showing the diaphragm supplied thereto fluid of an excessively high pressure, 
         FIG. 6A  is a cross-sectional view showing the normal state of the pressure regulator in accordance with a second embodiment of the present invention, 
         FIG. 6B  is a view similar to  FIG. 6A  showing a state of the pressure regulator where the supply pressure is increased excessively high, 
         FIG. 7A  is a cross-sectional view showing the normal state of the pressure regulator in accordance with a third embodiment of the present invention, 
         FIG. 7B  is a view similar to  FIG. 7A  showing a state of the pressure regulator where the supply pressure is increased excessively high, 
         FIG. 8  is a fragmentary enlarged cross-sectional view showing a first modification of the projection of the supporter and the projection of the cover casing in the first embodiment, 
         FIG. 9  is a fragmentary enlarged cross-sectional view showing a second modification of the projection of the supporter and the projection of the cover casing in the first embodiment, and 
         FIG. 10  is a fragmentary enlarged view showing a modification of the supporter in the third embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A pressure regulator in accordance with a first embodiment of the present invention will be described with reference to  FIGS. 1 to 3 , hereinbelow.  FIG. 1  is an exploded perspective view showing a pressure regulator  1  in accordance with a first embodiment of the present invention cut along a circumference around a shaft  2  passing through the center thereof by a range of about 90 degrees,  FIG. 2  is a fragmentary enlarged view of  FIG. 1 , and  FIG. 3  is a fragmentary enlarged view showing a lower part of the pressure regulator  1  of  FIG. 1  cut along a circumference around the shaft  2  by a range of about 90 degrees. 
     As shown in  FIG. 1 , the pressure regulator  1  has a housing  5  comprises a body casing  4 , a cover casing  6  and an introduction tube  8  mounted on the body casing  4 . The body casing  4  and the cover casing  6  respectively have bulgy portions  4   b  and  6   b  and have flanges  4   a  and  6   a  on their outer circumference which are similar to each other in shape. The bulgy portion  4   b  is formed with a through hole  24  ( FIGS. 2 and 3 ) in a position corresponding to the shaft  2 . The flange  4   a  of the body casing  4  and the flange  6   a  of the cover casing  6  buttes against each other and connected to each other, for instance, by screwing. 
     The butting face  10  ( FIG. 1 ) of the flange  4   a  is provided with an indented portion  10   a  over the entire inner circumference of the flange  4   a . A diaphragm  12  is disposed in the intended portion  10   a  and fixed between the flanges  4   a  and  6   a  in response to the fixture of the flanges  4   a  and  6   a . The diaphragm  12  is an elastic plate-like member such as of a rubber and has a flexible portion  12   a  ( FIG. 2 ) which is of a circular shape about the shaft  2 . The diaphragm  12  is provided with a circular opening  22  ( FIG. 2 ) opposed to the shaft  2 . A supporter  14  is disposed on an upper part of the diaphragm  12  inside the flexible portion  12   a.    
     On the side of the diaphragm  12  opposite to the supporter  14  is disposed a plunger  16 . The diaphragm  12 , supporter  14  and the plunger  16  are integrated and the integrated diaphragm  12 , supporter  14  and the plunger  16  are referred to as “movable body  15 ” altogether. The terms “upper” and “lower” as used here are as seen in  FIGS. 1 to 3 . The supporter  14  has a flat plate portion  14   a  ( FIG. 2 ) in contact with an upper surface  18  of the diaphragm  12  and a projection (abutment portion)  14   b  projecting upward from the flat plate portion  14   a . Though it is preferred that the supporter  14  be made of light-weight material such as polyoximethylene, the supporter  14  may be made of metal. The upper surface  26  ( FIG. 2 ) of the projection  14   b  is flat, and the projection  14   b  is formed with a female thread  14   c  ( FIG. 2 ) along the shaft  2 . 
     The plunger  16  is provided with a flat plate portion  16   a  on the lower side (a first surface)  20  of the diaphragm  12  and shafts  16   b  and  16   c  ( FIG. 2 ) extending in the vertical direction of the flat plate portion  16   a  along the shaft  2 . The shaft  16   b  projects upward through the opening  22  of the diaphragm  12  and the shaft  16   c  extends downward through the through hole  24  ( FIGS. 2 and 3 ) of the body casing  4 . The shaft  16   b  is provided with a male thread  17  which is in mesh with the female thread  14   c  of the supporter  14  to fasten the diaphragm  12  from the both sides. With this arrangement, the diaphragm  12  is sandwiched between the supporter  14  and the plunger  16  and is integrated therewith. It is preferred that film  29  ( FIG. 2 ) of a material low in frictional characteristics such as PET (polyethylene terephthalate) intervenes between the supporter  14  and the diaphragm  12 . With this arrangement, the diaphragm  12  cannot be deformed by the frictional force generated upon fastening the diaphragm  12  when the supporter  14  is brought into mesh with the shaft  16   b.    
     A projection (stopper portion)  28  is formed on the inner side of the bulgy portion  6   b  of the cover casing  6  opposed to the projection  14   b . The leading end face, or the lower surface  30  of the projection  28  is flat as the upper surface  26  of the supporter  14 . A small hole  34  ( FIG. 2 ) is formed in the center of the projection  28  to communicate external and the space  32  inside the bulgy portion  6   b . Since external is normally at the atmospheric pressure, the inside of the space  32  is held at the atmospheric pressure. A coiled compression spring (will be referred to as “pressure control spring”, herein below)  36  is fitted on the projections  14   b  and  28  of the supporter  14  and the cover casing  6 . The pressure control spring  36  normally urges downward the diaphragm  12  at a predetermined pressure by way of the supporter  14 . A space G ( FIG. 2 ) is normally assured between the projection  14   b  and the upper surface  26  of the supporter  14 . 
     The cover casing  6  is formed with a bulgy portion  6   c  which laterally bulges from the bulgy portion  6   b . The bulgy portion  6   c  is formed with a nozzle  40  which is formed therein a discharge port  38  and extends externally from the bulgy portion  6   c . In the cover casing  6  is further formed a cylindrical space  42  communicating with the discharge port  38  by a partition wall  6   d  ( FIG. 1 ). In a part of the body casing  4  opposed to the space  42  is formed a substantially cylindrical space  46  by a partition wall  4   c . An end face  7  ( FIGS. 1 and 2 ) of the partition wall  4   c  is seen in  FIGS. 1 and 2 , while the other end face of the partition wall  4   c  is in a position opposed to said one end face so that a groove  44  ( FIGS. 2 and 3 ) is formed between the end faces. In a part of the body casing  4  facing the space  46 , an upward facing annular indented portion  46   a  is formed. In the diaphragm  12 , a circular opening  37  is formed opposed to the spaces  42  and  46  ( FIG. 1 ). In the spaces  42  and  46 , a sleeve  50  having a flange  50   a  is disposed through the opening  37  in the diaphragm  12  with the flange  50   a  seated in the indented portion  46   a . The sleeve  50  is sized in its longitudinal direction so that a space is formed between its lower end and an inner surface  4   d  of the bulgy portion  4   b  ( FIGS. 2 and 3 ) and forms a passage which leads to the discharge port  38  fluid passing through the groove  44 . The sleeve  50  is formed, for instance, by polyoximethylene. 
     Between the bulgy portion  4   b  of the body casing  4 , the plunger  16  and the diaphragm  12 , a space, that is a pressure control chamber  52  is formed. An annular groove  54  ( FIG. 2 ) is formed on the leading end potion of the shaft  16   c  of the plunger  16  projecting downward through the through hole  24  of the bulgy portion  4   b  and an O-ring  56  is mounted in the annular groove  54 . The O-ring  56  forms the pressure control valve. That is, the O-ring  56  is driven up and down by the diaphragm  12  to change the flow of fluid between the shaft  16   c  and the through hole  24  of the bulgy portion  4   b , thereby changing the fluid pressure in the pressure control chamber  52 . The aforesaid pressure control spring  36 , the movable body  15 , the O-ring  56  and the like form the pressure control mechanism. An annular wall  58  extends downward to surround the leading end portion of the shaft  16   c  from the bulgy portion  4   b  of the body casing  4 . On the outer circumference of the base end of the annular wall  58 , a groove  60  ( FIG. 2 ) is formed and an O-ring  62  is mounted in the groove  60 . 
     A thread (not shown) may be formed on the outer side of the annular wall  58  to be able to be engaged with the aforesaid introduction tube  8 . The introduction tube  8  is a member to which a pressure vessel  400  to be described later ( FIG. 4 ) is connected, and comprises a partition wall  8   a  in the middle in the longitudinal direction thereof. The partition wall  8   a  is provided with an opening  76  which receives a lower shaft  70   c  of a plug  70 . A filter  64 , a joint  66 , a coiled compression spring  68  and the plug  70  are disposed in this order from upside between the partition wall  8   a  and the bulgy portion  4   b . The joint  66  is a substantially tubular member which has an upper wall  66   b  and is formed, for instance, by polyoximethylene. In the center of the upper wall  66   b  of the joint  66 , a hole  72  is formed and an annular flange  66   a  is formed between the upper wall  66   b  and the lower end  80  to extend toward the outside. 
     The filter  64  comprises a circular plate portion  64   a  and an annular wall  64   b  suspended from the outer periphery of the circular plate portion  64   a . The filter  64  covers the upper wall  66   b  of the joint  66 . In the assembled state, the flange  66   a  of the joint  66  abuts against a lower end  58   a  ( FIG. 3 ) of the annular wall  58  to support the filter  64  between a downward facing indented portion  58   b  and the upper wall  66   b  of the joint  66 . An intermediate chamber  21  into which the end portion of the shaft  16   c  of the plunger  16  projects is formed above the filter  64 . A plurality of grooves  67  ( FIG. 2 ) continuous in the vertical direction are formed on the inner surface  66   c  of the joint  66  spaced from each other in the direction of the inner circumference of the joint  66 . The grooves  67  form a passage through which pressurized fluid to be supplied flows. 
     The plug  70  is like a pin formed by stainless steel or polyoximethylene and is provided with an annular flange  70   a  in its upper portion. An upper shaft  70   b  projecting upward beyond the flange  70   a  has a diameter able to be inserted inside the spring  68 . The lower shaft  70   c  projecting downward beyond the flange  70   a  tapers toward a lower end  74 . An O-ring  78  is mounted in the vicinity of the flange  70   a  of the lower shaft  70   c.    
     When the introduction tube  8  is incorporated in the annular wall  58 , the spring  68  and the plug  70  are held between upper wall  66   b  of the joint  66  and the partition wall  8   a  of the introduction tube  8 . At this time, the flange  70   a  of the plug  70  is urged downward by the spring  68 , and the O-ring  78  is pressed between the flange  70   a  and the partition wall  8   a . The O-ring  78  is in close contact with the flange  70   a  and the partition wall  8   a  under the urging force of the spring  68  when the pressure vessel  400  is not connected to the introduction tube  8 . With this arrangement, the pressurized fluid in the pressure regulator  1  is prevented from externally leaking between the lower shaft  70   c  of the plug  70  and the opening  76  of the partition wall  8   a.    
     Use of the pressure vessel  400  such as a cartridge of a fuel cell connected to the pressure regulator  1  structured as described above will be described with reference to  FIGS. 4  ( 4 A and  4 B), hereinbelow.  FIG. 4  show the cross-sections of the pressure regulator  1  to which the pressure vessel  400  is connected.  FIG. 4A  shows a normal state of the pressure regulator  1 , while  FIG. 4B  shows a state of the pressure regulator  1  where the pressure therein is increased excessively high. In  FIG. 4 , only a part of the pressure vessel is shown in cross-section. In  FIG. 4 , a fitting portion  402  inserted into the introduction tube  8  and a body portion  404  on which the fitting portion  402  is mounted are shown as a pressure vessel  400 . An ejecting port  406  vertically extends through the fitting portion  402 . A valve body  408  which is normally urged upward by a spring  410  to prevent ejection of the fluid in the pressure vessel  400  is held for sliding motion inside the ejecting port  406 . 
     As shown in  FIGS. 4A and 4B , the plug  70  is pressed upward by the valve body  408  when the pressure vessel  400  is mounted on the pressure regulator  1 . The opening  76  of the introduction tube  8 , which has been closed by the O-ring  78 , is thereby opened and the pressurized fluid passes by the opening  76 , the groove  67  inside the joint  66  and the filter  64  in this order. In the initial state of connection of the pressure vessel  400 , since the fluid pressure in the pressure control chamber  52  is low, the diaphragm  12  is in a state where it is urged downward by the pressure control spring  36 . Accordingly, since the O-ring  56  for sealing the through hole  24  of the body casing  4  is moved downward away from the through hole  24 , the sealing of the through hole  24  has been released. Accordingly, the pressurized fluid passing by the passage  67 , the filter  64 , the intermediate chamber  21 , the space between the through hole  24  and the shaft  16   c , the pressure control chamber  52  and the sleeve  50  is supplied to an external device such as a fuel cell (not shown) through the discharge port  38 . 
     In a normal state of use, the diaphragm  12  is set so that the pressure in the pressure control chamber  52  is a predetermined pressure under the force of the pressure control spring  36  with respect to a pressure of the supplied fluid, for instance, 900 KPa to 1 MPa. That is, when the pressure of the fluid to be supplied from the pressure vessel  400  exceeds the pressure of the fluid to be supplied, the fluid in the pressure control chamber  52  presses upward the diaphragm  12  overcoming the pressure control spring  36 . As a result, the shaft  16   c  of the plunger  16  is moved upward and the O-ring seals the through hole  24  of the body casing  4 , whereby the pressurized fluid is prevented from flowing into the pressure control chamber  52  any more. The pressure applied to the diaphragm  12  from the pressurized fluid, strictly speaking, includes not only the pressure in the pressure control chamber  52  but also a pressure applied to the pressure control valve including the O-ring  56  in the intermediate chamber  21 . That is, since a pressure equal to the primary pressure in the intermediate chamber  21 ×projected area of the pressure control valve has been applied to the pressure control valve, the pressure control valve can close under the pressurized fluid and/or the O-ring  56  can slide into the valve seat to be deformed. When the pressure in the pressure control chamber  52  lowers, the shaft  16   c  of the plunger  16  is moved downward to open the through hole  24  under the urging force of the pressure control spring  36  to permit the pressurized fluid to flow into the pressure control chamber  52  again. 
     Thus, the diaphragm  12  constantly moves (vibrates) up and down in response to fluctuation in the fluid pressure. However, since the distance of up and down movement is very slight, for instance, about 0.3 mm, the aforesaid space G, that is, the space between the upper surface  26  of the projection  14   b  and the lower surface  30  of the projection  28  of the cover casing is held substantially constant in dimensions. Though in  FIG. 4A  representing a state where the pressurized fluid flows, the O-ring  56  is shown to be in contact with the body casing  4 , actually there is a very little space between the O-ring  56  and the body casing  4 , and the pressurized fluid can pass therethrough. 
     However, when the fluid pressure supplied from the pressure vessel  400  becomes excessively high for some reason, for instance, due to increase in the temperature of the pressure vessel  400  or collapse of the pressure vessel  400 , the diaphragm  12  behaves in a way different from the normal as shown in  FIG. 4B . That is, even if the through hole  24  is sealed by the O-ring  56 , for instance, by an abnormally high pressure of the supplied fluid pressure, for instance, a pressure of 2 MPa to 3 MPa, the shaft  16   c  of the plunger  16  is pressed further upward beyond the intermediate chamber  21 , that is, into the pressure control chamber  52 .  FIG. 5  shows the O-ring  56  in this state. 
       FIG. 5  shows a state of the diaphragm  12  when an excessively high pressure fluid is supplied and an enlarged view of the area V surrounded by the chained line in  FIG. 4B . As can be seen from  FIG. 5 , the O-ring  56  starts to be deformed pressed by the body casing  4  in response to the upward movement of the shaft  16   c  of the plunger  16 . In the state shown in  FIG. 5 , the O-ring  56  can still resiliently return to the original state. At this time, the upper surface  26  of the projection  14   b  of the supporter  14  abuts against the lower surface  30  of the projection  28  of the cover casing  6  which forms a part of the housing  5  and the diaphragm  12  is not displaced upward any more. With this arrangement, the O-ring  56  is broken or the shaft  16   c  is withdrawn upward from the through hole  24  and the pressurized fluid is prevented from leaking from the intermediate chamber  21  to the pressure control chamber  52 . Though the intermediate chamber  21  and the pressure control chamber  52  are in communication with each other through a small space if the O-ring  56  is broken, the pressurized fluid is prevented from leaking to the external from the opening  76  even if the pressure vessel  400  is removed since the opening  76  is sealed by the plug  70  and the O-ring  78 . 
     A pressure regulator  100  in accordance with a second embodiment of the present invention will be described with reference to  FIG. 6  hereinbelow.  FIG. 6  show a cross-section of the pressure regulator  100  in accordance with the second embodiment of the present invention and  FIGS. 6A and 6B  respectively show a normal state and a state where the pressure therein is increased excessively high of the pressure regulator  100 . The pressure regulator  100  comprises a body casing  104 , a cover casing  106 , a diaphragm  112  disposed between the body casing  104  and the cover casing  106 , a supporter  114  and a plunger  116  holding the diaphragm  112  on both sides, an introduction tube  108  which is laterally mounted on a side of the body casing  104  and has an inlet port  176 , and a filter  164 , a spring  168 , and a plug  170  disposed in the introduction tube  108 . The diaphragm  112 , supporter  114  and the plunger  116  are altogether referred to as “the movable body”. The body casing  104 , the cover casing  106  and the introduction tube  108  form a housing  105 . In  FIG. 6 , the pressure vessel  400  is abbreviated. 
     As in the first embodiment, the body casing  104  is provided with an annular wall  158  projecting downward integrally therewith opposite to the plunger  116 . On the outer side of the annular wall  158 , a lid  196  is mounted on the annular wall  158 , for instance, by screwing. With this arrangement, an intermediate chamber  161  is formed in the annular wall  158 . Further, the body casing  104  is integrally formed with another annular wall  158 ′ similar to the annular wall  158  to laterally extend. On said another annular wall  158 ′, an introduction tube  108  similar to that in the first embodiment is mounted. Since the structure inside the introduction tube  108  and the structure of the diaphragm  112  and the supporter  114  and the plunger  116  supporting the diaphragm  112  are the same as those in the first embodiment, description in detail will be abbreviated. 
     In the body casing  104 , a flow passage  163  which is the passage of the fluid from the introduction tube  108  to the intermediate chamber  161  and from the intermediate chamber  161  to the pressure control chamber  152  is formed. Further, the body casing  104  is provided with a nozzle  140  opposite to the introduction tube  108 . The nozzle  140  is provided with a discharge port  138  communicating with the pressure control chamber  152 . 
     The supporter  114  has a projection (abutment portion)  114   b  whose upper surface  126  is flat also in the second embodiment, and the lower surface  130  of the projection (stopper portion)  128  of the cover casing  106  is also flat. The supporter  114  is urged downward by the pressure control spring  136 . A space G is normally formed between the upper surface  126  and the lower surface  130 . Also in the second embodiment, when the fluid pressure supplied becomes excessively high, the shaft  116   c  of the plunger  116  is moved upward and the upper surface  126  of the projection  114   b  of the supporter  114  abuts against the lower surface  130  of the projection  128  of the cover casing  106  as shown in  FIG. 6B , whereby excessive deformation of the diaphragm  112  is prevented. 
     A pressure regulator  200  in accordance with a third embodiment of the present invention will be described with reference to  FIGS. 7  ( 7 A and  7 B) hereinbelow.  FIG. 7  show a cross-section of the pressure regulator  200  in accordance with the third embodiment of the present invention and  FIGS. 7A and 7B  respectively show a normal state and a state where the pressure therein is increased excessively high of the pressure regulator  200 . The pressure regulator  200  has structure similar to the pressure regulator  1  of the first embodiment. That is, the pressure regulator  200  comprises a body casing  204 , a cover casing  206 , a diaphragm  212  disposed in the body casing  204  and the cover casing  206 , a supporter  214  and a plunger  216  holding the diaphragm  212 , an introduction tube  208  which has an inlet port  276 , and a filter  264 , a joint  266 , and a plug  270  disposed in the similar positions to the pressure regulator  1  of the first embodiment. The diaphragm  212 , supporter  214  and the plunger  216  are altogether referred to as “the movable body”. The body casing  204 , the cover casing  206  and the introduction tube  208  form a housing  205 . The pressure regulator  200  in accordance with the third embodiment mainly differs from the pressure regulator of the first embodiment in that the discharge port  238  and the nozzle  240  are provided on the body casing  204 . In  FIG. 7 , the pressure vessel  400  is abbreviated. Accordingly, the sleeve  50  in the first embodiment is not employed in the third embodiment. 
     The supporter  214  has a projection (abutment portion)  214   b  whose upper surface  226  is flat also in the third embodiment, while the cover casing  206  is formed with a downward projection (stopper portion)  228  and the lower surface  230  of the projection  228  of the cover casing  206  is also flat. On the outer periphery of the projection  214   b  of the supporter  214  and the projection  228  of the cover casing  206 , a pressure control spring  236  is disposed in a compressed state. The supporter  214  is urged downward under predetermined force by the pressure control spring  136 . A space G is normally formed between the upper surface  226  and the lower surface  230 . Also in the third embodiment, when the fluid pressure supplied becomes excessively high, the plunger  216  is moved upward and the upper surface as shown in  FIG. 7B  and the diaphragm  212  is moved upward, whereby the upper surface  226  of the projection  214   b  of the supporter  214  abuts against the lower surface  230  of the projection  228  of the cover casing  206  and excessive deformation of the diaphragm  112  is prevented. 
       FIG. 8  is a fragmentary enlarged cross-sectional view showing a first modification of the projection  14   b  of the supporter  14  and the projection  228  of the cover casing  6  in the first embodiment, and  FIG. 9  is a fragmentary enlarged cross-sectional view showing a second modification of the projection  14   b  of the supporter  14  and the projection  228  of the cover casing  6  in the first embodiment. In  FIG. 8 , the supporter  514  of the pressure regulator  500  comprises a circular flat plate portion  514   a  and a shaft  514   c  which projects upward and downward from the center of the flat plate portion  514   a . The lower part of the shaft  514   c  is threaded to mesh with the plunger  516 . The flat plate portion  514   a  is formed with an annular projection (abutment portion)  514   b  projecting upward coaxially with the shaft  514   c . An annular groove or an annular recess  514   d  for receiving a pressure control spring  536  is formed in the projection  514   b.    
     An upward projecting bearing portion  506   e  is formed in the cover casing  506  in a position opposed to the projection  514   b , and another annular groove or an annular recess  506   f  for receiving a pressure control spring  536  is formed in the bearing portion  506   e . The pressure control spring  536  is disposed between the recess  506   f  in the bearing portion  506   e  and the recess  514   d  of the projection  514   b  of the supporter  514  and urges downward the diaphragm  512  under a predetermined pressure by way of the supporter  514 . In the first modification of the first embodiment, when the fluid pressure supplied becomes excessively high, the leading end or the upper surface  526  of the projection  514   b  abuts against the inner side (stopper portion)  506   g  of the cover casing  506  at a part opposed to the leading end or the upper surface  526 . A space G is normally formed between the upper surface  526  and the inner side  506   g . The diaphragm  512 , supporter  514  and the plunger  516  are altogether referred to as “the movable body  515 ”. 
     A second modification of the projection  14   b  of the supporter  14  and the projection  28  of the cover casing  6  in the first embodiment of the present invention will be described with reference to  FIG. 9 , hereinbelow. In the pressure regulator  600  shown in  FIG. 9 , the supporter  614  has substantially the same structure as in the first modification. That is, the supporter  614  has an upward facing shaft (abutment portion)  614   b  at the center thereof. Whereas, a projection (stopper portion)  628  is formed in the annular groove or the recess  606   f  of the bearing portion  606   e  similar to that in the first modification to extend downward opposed to the shaft  614   b . The lower surface  630  of the projection  628  is suspended to the vicinity of the upper surface  626  of the shaft  614   b  and a predetermined gap G is formed between the lower surface  630  and the upper surface  626 . In the second modification, the upper surface  626  of the shaft  614   b  of the supporter  614  abuts against the lower surface  630  of the projection  628  of the cover casing  606  when the fluid pressure supplied becomes excessively high. Also in the second modification, the diaphragm  612 , supporter  614  and the plunger  616  altogether form the movable body  615 . 
     As a modification of the pressure regulator  200  in accordance with the third embodiment described above, a supporter  714  of a pressure regulator  700  will be described with reference to  FIG. 10 , hereinbelow.  FIG. 10  is a partly enlarged view of a modification of the supporter employed in the third embodiment. The pressure regulator  700  is of the same structure as the pressure regulator  200  in accordance with the third embodiment described above except that the supporter  714  of the pressure regulator  700  has a different shape. That is, the supporter  714  is like a circular plate and has a female thread  714   c  at the center thereof and at the same time, is provided with an upward facing annular groove  714   e  formed coaxially with the female thread  714   c . The female thread  714   c  is adapted to engage with a male thread  717  formed on the shaft  716   b  of the plunger  16 . A pressure control spring  736  is disposed in the annular groove  714   e . On the other hand, the cover casing  706  is provided with a projection (stopper portion)  728  which has a diameter accommodated in the pressure control spring  736  is formed opposed to the supporter  714 . A predetermined gap G is formed between the lower surface  730  of the projection  728  and the upper surface  726  of the 3 supporter  714 . In this modification, the upper surface  726  of the supporter  714  abuts against the lower surface  730  of the projection  728  when the fluid pressure supplied becomes excessively high. In this case, the abutment portion is the supporter  714  itself. Also in this modification, the diaphragm  712 , supporter  714  and the plunger  716  altogether form the movable body  715 . 
     Any one of the pressure control springs  36 ,  136 ,  236 , and  736  employed in the first to third embodiments and the modification of the third embodiment described above is disposed on the outside of the projections  14   b  and  28 , the projections  114   b  and  128 , and the projections  214   b  and  228  and is thick in the line diameter while short in total length. On the other hand, any one of the pressure control springs  536 , and  636  employed in the first and second modifications of the first embodiment described above is thin in the line diameter and long in total length. Generally, in the former pressure control spring, that is, in a pressure control spring which is thick in the line diameter and short in total length, the spring constant is large. Whereas, in the latter pressure control spring, that is, in a pressure control spring which is thin in the line diameter and long in total length, the spring constant is small. In the case of a spring which is small in spring constant, fluctuation of load applied to the diaphragm in positions to which the diaphragm is displaced in the vertical direction can be minimized, and the secondary pressure in the pressure control chamber can be set in a wide range. However, if it is not necessary to set the secondary pressure in the pressure control chamber, the pressure regulator may be small in size in the vertical direction. The shape of the pressure control spring may be suitably set so that the secondary pressure required to the fuel supplying body side such as the fuel cell can be satisfied. Accordingly, it is possible to dispose a pressure control spring which is large in spring constant and thickness and small in length between the projections  514   b  and  614   b  and the cover casings  506  and  606  in the first and second modifications shown in  FIGS. 9 and 10 . 
     Though embodiments of the present invention have been described above, when the pressure vessel  400  is mounted on the pressure regulators  1 ,  100  and  200 , it is necessary a fixture system for holding the pressure vessel  400  in the mounted position. The fixture system may comprise simply a spring member such as a coiled compression spring or a leaf spring. Otherwise, the fixture system may comprise a fastener mechanism disclosed in Japanese Unexamined Patent Application No. 2004-266463 “PRESSURE REGULATOR” which we have filed Sep. 14, 2004. Other fixture system is variously conceivable. However, since being deviated from the scope of the invention, they will not be described in detail.