Abstract:
The flow controller is capable of optionally controlling flow volume of controlled flow and reducing weight and a production cost. The flow controller comprises: a main body having a first flow path and a second flow path; a ring packing for sealing the flow paths; a rod-shaped flow control member tightly pierced through the ring packing and capable of moving with respect to the ring packing, the flow control member having a third flow path; operation means for moving the flow control member so as to control the flow volume; a fourth flow path provided outside of the ring packing; and a check valve prohibiting a fluid to flow from the second flow path to the first flow path via the fourth flow path and allowing the fluid to flow from the first flow path to the second flow path via the fourth flow path.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates to a flow controller, which has a first port and a second port and which is capable of flowing a fluid from the second port to the first port as controlled flow, whose flow volume is controlled, and flowing the fluid from the first port to the second port as free flow.  
         [0002]     A conventional flow controller is disclosed in Japanese Patent Kokai Gazette No. 6-331059, and the conventional flow controller is shown in  FIG. 15 .  
         [0003]     A main body  80  of the flow controller has an opening section  82 , which acts as a first port, and an opening section  84 , which acts as a second port. A control member  88  having a control hole  86 , through which a fluid passes, is provided in a flow path, which makes the first port  82  and the second port  84  communicate each other. A needle  90  is capable of moving in the axial direction and entering the control hole  86 . By varying a length of inserting a tapered end of the needle  90  into the control hole  86 , a sectional area of a clearance formed in the flow path, through which the fluid can pass, is varied, so that flow volume of controlled flow can be controlled (see paragraph 0015 of the Japanese patent kokai gazette No. 6-331059). The axial movement of the needle  90  is adjusted by manually rotating a rotary member  92 .  
         [0004]     An outer flow path, which makes the first port  82  and the second port  84  communicate each other, is formed outside of the control member  88 . A diaphragm  94 , which acts as a check valve, is provided in the outer flow path. The diaphragm  94  prohibits the fluid to flow from the second port  84  to the first port  82  via the outer flow path; the diaphragm  94  allows the fluid to flow from the first port  82  to the second port  84  via the outer flow path (see paragraphs 0013 and 0015-0017 of the Japanese patent kokai gazette No. 6-331059).  
         [0005]     As described above, in the conventional flow controller shown in  FIG. 15 , the flow volume of the controlled flow is controlled by adjusting the sectional area of the clearance between an outer face of the needle  90  and an inner face of the control hole  86 . The sectional area can be adjusted by moving the needle  90  with respect to the control hole  86 .  
         [0006]     However, it is difficult to precisely control the flow volume of the controlled flow when the flow volume is small. This disadvantage will be explained with reference to  FIGS. 16A and 16B .  
         [0007]     In  FIG. 16A , no clearance is formed between the outer face of the needle  90  and the inner face of the control hole  86 . Namely, no controlled flow passes. In this state, the needle  90  is moved so as to form the clearance C between the outer face of the needle  90  and the inner face of the control hole  86 . The state of forming the clearance C is shown in  FIG. 16B . The clearance C is formed around an entire circumference of the needle  90 .  
         [0008]     To flow the controlled flow with small flow volume, the needle  90  in the state shown in  FIG. 16A  is slightly moved. However, the clearance C is formed around the entire circumference of the needle  90 , so the sectional area of the clearance C rapidly increases. Therefore, it is difficult to precisely control the flow volume of the controlled flow when the flow volume thereof is small.  
         [0009]     Further, fluid resistance strongly works to the tapered needle  90 , so the needle  90  must be made of a high rigidity material, e.g., steel, so as to secure enough strength of the needle  90 . Therefore, it is difficult to reduce weight and a production cost of the flow controller.  
       SUMMARY OF THE INVENTION  
       [0010]     The present invention was conceived to solve the above described problems.  
         [0011]     An object of the present invention is to provide a flow controller, which is capable of optionally controlling flow volume of controlled flow and reducing weight and a production cost.  
         [0012]     To achieve the object, the present invention has following structures.  
         [0013]     Namely, the flow controller of the present invention comprises:  
         [0014]     a main body having a first flow path, which is communicated to a first port, and a second flow path, which is communicated to a second port;  
         [0015]     a ring packing being provided between the first flow path and the second flow path so as to seal the first flow path and the second flow path;  
         [0016]     a rod-shaped flow control member being tightly pierced through the ring packing and capable of relatively moving, in the axial direction, with respect to the ring packing, the flow control member having a third flow path, whose end is opened at least in an outer circumferential face thereof and which communicates the first flow path to the second flow path via the ring packing, wherein flow volume of a fluid flowing in the third flow path is controlled by adjusting a position of the flow control member with respect to the ring packing;  
         [0017]     operation means for relatively moving the ring packing and/or the flow control member in the axial direction of the flow control member;  
         [0018]     a fourth flow path being provided outside of the ring packing so as to communicate the first flow path to the second flow path; and  
         [0019]     a check valve prohibiting the fluid to flow from the second flow path to the first flow path via the fourth flow path and allowing the fluid to flow from the first flow path to the second flow path via the fourth flow path.  
         [0020]     With this structure, the flow volume of the fluid flowing in the third flow path can be optionally controlled by adjusting aperture of the third flow path, which corresponds to the position of the flow control member with respect to the ring packing. Unlike the conventional flow controller, fluid resistance does not strongly work to a weak part, e.g., tapered needle, because the flow volume is controlled by the third flow path, which is formed around the rod-shaped flow control member, and the ring packing. Therefore, the flow control member can be composed of a light and inexpensive material, e.g., plastic.  
         [0021]     In the flow controller, a circumferential width of the end of the third flow path, which is opened in the outer circumferential face of the flow control member, may be gradually increased toward one end of the flow control member.  
         [0022]     In the flow controller, the third flow path may be a bifurcated notch, which is formed by notching the one end of the flow control member in the axial direction and whose width is gradually increased toward the one end thereof. With this structure, the third flow path for optionally controlling the flow volume of controlled flow can be constituted with a simple shape.  
         [0023]     In the flow controller, the bifurcated notch may be opened in both side faces of the flow control member, and notching depths of the bifurcated notch in the both side faces may be mutually different. With this structure, the first flow path and the second flow path can be communicated via the bifurcated notch in the one side face, whose depth is deeper than that in the other side face. Therefore, the flow volume can be precisely controlled even if the flow volume of the controlled flow is small.  
         [0024]     In the flow controller, the third flow path may be opened in the one end face of the flow control member and the outer circumferential face thereof, and a sectional area of the third flow path perpendicular to the axial line of the flow control member may be gradually increased toward the one end of the flow control member. With this structure, the sectional area is gradually reduced toward the other end of the flow control member. In comparison with the conventional flow controller, in which the flow volume is controlled by adjusting the sectional area of the clearance around the outer circumferential face of the needle, the flow controller of the present invention is capable of precisely controlling the flow volume even if the flow volume of the controlled flow is small.  
         [0025]     In the flow controller, the operation means may have a screw section, which is connected to the ring packing and/or the flow control member and a part of which is projected from the main body as a knob for rotating the screw section, and  
         [0026]     the screw section may relatively move the ring packing and/or the flow control member in the axial direction of the flow control member by rotating the knob. With this structure, the simple operation means can be constituted.  
         [0027]     In the flow controller, the main body may be a cylinder, in which the first flow path and the second flow path are respectively formed in both end parts and a through-hole is formed in an outer wall constituting one of the first flow path and the second flow path,  
         [0028]     the operation means may be coaxially provided to the main body, cover at least a part of an outer circumferential face of the main body and the through-hole, and have a cylindrical knob, which can be manually rotated with respect to the main body and in which a first screw section is formed in an inner circumferential face,  
         [0029]     a projected section may be projected in the direction perpendicular to the axial line of the flow control member from the end part of the flow control member, which corresponds to the one of first flow path and the second flow path, until reaching the inner circumferential face of the knob via the through-hole and have a second screw section, which is screwed with the first screw section of the knob, and  
         [0030]     the flow control member may be moved in the axial direction thereof by the first screw section and the second screw section, which are operated by rotating the knob. With this structure, the cylindrical main body and the cylindrical knob can be coaxially arranged, so the flow controller can be downsized and have a simple external shape. Further, hoses connected to the first and second ports can be coaxially arranged with the main body, so a required space for installing the flow controller can be reduced.  
         [0031]     In the flow controller, the first port and the second port may be provided to the main body, their axial lines may be orthogonally arranged,  
         [0032]     one end part of the flow control member may be moved toward one of the first port and the second port, the other end part of the flow control member may have a first screw section,  
         [0033]     the operation means may have a second screw section, which is screwed with the first screw section, and a knob, which is projected from the other end part of the flow control member until outside of the main body and which can be manually rotated, and  
         [0034]     the flow control member may be moved in the axial direction thereof by the first screw section and the second screw section, which are operated by rotating the knob. With this structure, the first port and the second port are perpendicularly arranged, and the knob is projected. Therefore, a user can easily operate the knob.  
         [0035]     In the flow controller, the check valve may include a valve body for closing the fourth flow path formed around the ring packing, the check valve may be integrated with the ring packing and formed into a cone shape, which is inclined and extended from the ring packing toward the second flow path. With this structure, the check valve and the ring packing are integrated, so that the flow controller can be simplified and downsized, and number of parts can be reduced.  
         [0036]     In the flow controller, a circular projection may be formed, in an inner circumferential face of the main body, along an outer circumferential face of the cone-shaped valve body, and  
         [0037]     at least one through-hole may be formed in the circular projection as the fourth flow path. With this structure, the valve body and the ring packing can be held in the main body by the circular projection, and the compact fourth flow path can be formed.  
         [0038]     By employing the flow controller of the present invention, the flow volume of the controlled flow can be optionally controlled. Further, weight and a production cost of the flow controller can be reduced. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0039]     Embodiments of the present invention will now be described by way of examples and with reference to the accompanying drawings, in which:  
         [0040]      FIG. 1  is a perspective view of a flow controller of a first embodiment;  
         [0041]      FIG. 2  is a sectional view of the flow controller of the first embodiment;  
         [0042]      FIG. 3  is a perspective view of a main body of the flow controller of the first embodiment;  
         [0043]      FIG. 4  is a perspective view of a knob of the flow controller of the first embodiment;  
         [0044]      FIG. 5  is a perspective view of a rubber member (a ring packing and a valve body) of the flow controller of the first embodiment;  
         [0045]      FIG. 6  is a perspective view of a flow control member of the flow controller of the first embodiment;  
         [0046]      FIG. 7  is a perspective view of a second projection part of the flow control member of the flow controller of the first embodiment;  
         [0047]      FIG. 8  is a perspective view of a flow controller of a second embodiment;  
         [0048]      FIG. 9  is a sectional view of the flow controller of the second embodiment;  
         [0049]      FIG. 10  is a perspective view of a main body of the flow controller of the second embodiment;  
         [0050]      FIG. 11  is a perspective view of a knob of the flow controller of the second embodiment;  
         [0051]      FIG. 12  is a perspective view of a flow control member of the flow controller of the second embodiment;  
         [0052]      FIG. 13A  is a perspective view of a stopper of the flow controller of the second embodiment seen from the first flow path side;  
         [0053]      FIG. 13B  is a perspective view of a stopper of the flow controller of the second embodiment seen from the knob side;  
         [0054]      FIG. 14  is an explanation view of another flow control member;  
         [0055]      FIG. 15  is a sectional view of the conventional flow controller;  
         [0056]      FIG. 16A  is a partial sectional view of the conventional flow controller, wherein no clearance is formed between a needle and a control hole; and  
         [0057]      FIG. 16B  is a partial sectional view of the conventional flow controller, wherein a clearance is formed between the needle and the control hole. 
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0058]     Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.  
       First Embodiment  
       [0059]     A perspective view of a flow controller S 1  of a first embodiment is shown in  FIG. 1 , and a sectional view thereof is shown in  FIG. 2 .  
         [0060]     As shown in  FIG. 1 , the flow controller S 1  comprises a cylindrical main body  2  and a cylindrical knob  4 , which is coaxially arranged with the main body  2  and covers a part of an outer circumferential face of the main body  2 . A user is capable of rotating the knob  4  with respect to the main body  2 .  
         [0061]     A first nipple member  6 , in which a first port  6   a  is formed, and a second nipple member  8 , in which a second port  8   a  is formed, are respectively attached to both ends of the main body  2 . As shown in  FIG. 2 , fluid passageways P 1  and P 2 , e.g., hoses, which introduce a fluid into and discharge the fluid from the main body  2 , are respectively connected to the ports  6   a  and  8   a.    
         [0062]     The main body  2  has a first flow path  2   a,  which is communicated to the first port  6   a,  and a second flow path  2   b,  which is communicated to the second port  8   a.    
         [0063]     Through-holes  2   c  and  2   d  are oppositely formed in an outer wall of the main body  2 , which constitutes the first flow path  2   a  (see  FIGS. 2 and 3 ).  
         [0064]     As shown in  FIG. 2 , the knob  4  covers a part of the outer circumferential face of the main body  2  including the through-holes  2   c  and  2   d.    
         [0065]     A cover section  2   e  is formed in one end part of the main body  2 . One end part  4   b  of the knob  4  is inserted in the cover section  2   e.  Namely, an outer cylinder section (the cover section  2   e ) apart from the outer circumferential face of the main body  2  is formed in the one end part of the main body  2 , and the one end part  4   b  of the knob  4  is inserted in a space between an inner circumferential face of the outer cylinder section (the cover section  2   e ) and the outer circumferential face of the main body  2 .  
         [0066]     The first nipple member  6  is fitted in the other end of the main body  2 . The first nipple member  6  further has a flange section  6   b,  which is radially outwardly extended along the other end face of the main body  2 , so that the knob  4  can be retained in the main body  2 . Namely, the knob  4  is clamped between the cover section  2   e  and the flange section  6   b,  so that the knob  4  can be retained on the outer circumferential face of the main body  2 .  
         [0067]     A plurality of recesses are formed in an innermost face  2   f  of the cover section  2   e  (see  FIG. 2 ) and arranged in the circumferential direction. Projections  4   c,  which can engage with the recesses, are formed in one end face of the knob  4 , which faces the recesses (see  FIG. 4 ). When the user turns the knob  4 , the projections  4   c  run on the recesses. On the other hand, when the user stops turning the knob  4  at an optional rotational position, the projections  4   c  engages with the recesses, so that the knob  4  can be retained at that position.  
         [0068]     A first screw section  4   a  is formed in a part of an inner circumferential face of the knob  4 , which corresponds to the through-holes  2   c  and  2   d.  Namely, the first screw section  4   a  of the knob  4  faces the first flow path  2   a  of the main body  2  through the through-holes  2   c  and  2   d.    
         [0069]     A circular projection  2   g  is formed in an inner circumferential face of the main body  2  and disposed between the flow paths  2   a  and  2   b.  A plurality of through-holes  2   h  are formed in the circular projections  2   g  as fourth flow paths, and they are arranged in the circumferential direction.  
         [0070]     A rubber member  10  is attached to the circular projection  2   g  of the main body  2 , which is disposed between the first flow path  2   a  and the second flow path  2   b.  In the rubber member  10 , a ring packing  10   a,  which seals the first flow path  2   a  and the second flow path  2   b,  and a valve body  10   b,  which is formed into a cone shape, extended from the ring packing  10   a  toward the second flow path  2   b  and capable of closing one ends of the fourth flow paths  2   h,  are integrated (see  FIGS. 2 and 5 ).  
         [0071]     As shown in  FIG. 2 , the cone-shaped valve body  10   b  is obliquely extended outward from an inner part of the ring packing  10   a.  With this structure, a neck section  10   c  is formed between the ring packing  10   a  and the valve body  10   b.    
         [0072]     A surface  2   i  of the circular projection  2   g  on the second flow path  2   b  side is formed into a female tapered face along an outer circumferential face of the cone-shaped valve body  10   b  of the rubber member  10 . On the other hand, a surface  2   j  of the circular projection  2   g  on the first flow path  2   a  side is formed into a vertical face.  
         [0073]     The outer circumferential face of the cone-shaped valve body  10   b  of the rubber member  10  is arranged along the slope surface  2   i,  and the circular projection  2   g  is engaged with the neck section  10   c,  so that the rubber member  10  is retained in the main body  2 .  
         [0074]     The cone-shaped valve body  10   b  is arranged along the slope surface  2   i  so as to close the one ends of the fourth flow paths  2   h.    
         [0075]     When fluid pressure in the first flow path  2   a  and the fourth flow paths  2   h  are higher than that in the second flow path  2   b,  the valve body  10   b  is pressed and deformed by the pressure of the fluid in the fourth flow paths  2   h,  so that the fluid flows from the first flow path  2   a  to the second flow path  2   b  via the fourth flow paths  2   h.    
         [0076]     On the other hand, when the fluid pressure in the second flow path  2   b  is higher than that in the first flow path  2   a  and the fourth flow paths  2   h,  the valve body  10   b  is pressed by the fluid pressure in the second flow path  2   b,  but the valve body  10   b  is pressed onto the slope surface  2   i  and closes the one ends of the fourth flow paths  2   h.  Therefore, the fluid cannot flow from the second flow path  2   b  to the first flow path  2   a.    
         [0077]     Namely, the valve body  10   b  works as a check valve, which prohibits the fluid to flow from the second flow path  2   b  to the first flow path  2   a  via the fourth flow paths  2   h  and allows the fluid to flow from the first flow path  2   a  to the second flow path  2   b  via the fourth flow paths  2   h.    
         [0078]     A rod-shaped flow control member  12  is provided in the main body  2 . The flow control member  12  is tightly pierced through the ring packing  10   a  and capable of moving, in the axial direction, with respect to the ring packing  10   a.    
         [0079]     The flow control member  12  has a third flow path  12   b,  which is opened in one end face  12   a  and an outer circumferential face of the flow control member  12  and which makes the first flow path  2   a  communicate to the second flow path  2   b  via the ring packing  10   a.  Flow volume of the fluid flowing in the third flow path  12   b  can be controlled by adjusting the relative axial position of the flow control member  12  with respect to the ring packing  10   a.    
         [0080]     A bifurcated notch (an opening section) is formed in the one end  12   a  part. The bifurcated notch is opened in the one end face  12   a  and the outer circumferential face of the flow control member  12  as a V-shaped notch. By forming the bifurcated (V-shaped) notch, the one end  12   a  part of the flow control member is formed into a V-shape (see  FIGS. 2 and 6 ). The space in the V-shape acts as the third flow path  12   b.    
         [0081]     As shown in  FIGS. 2 and 6 , the width of the third flow path  12   b  or the V-shaped notch (the opening section) is gradually increased toward the one end  12   a.  Namely, the width of the third flow path  12   b  in the circumferential direction of the flow control member  12  is gradually increased toward the one end  12   a,  and a sectional area of the third flow path  12   b  perpendicular to the axial line of the flow control member  12  is gradually increased toward the one end  12   a.    
         [0082]     In the state shown in  FIG. 2 , the one end  12   a  part of the flow control member  12  corresponds to the ring packing  10   a.  By moving the flow control member  12  leftward, a sectional area of the third flow path  12   b  corresponding to the ring packing  10   a  and opening areas of the open ends of the third flow path  12   b,  which are opened in the side faces  12   c  and  12   d  of the flow control member  12 , on the first flow path  2   a  side with respect to the ring packing  10   a  are gradually reduced. Therefore, flow volume of the fluid flowing in the third flow path  12   b  is reduced. More precisely, the sectional area of the third flow path  12   b  in the ring-shaped part of the ring packing  10   a  and the smaller opening part of the open ends of the third flow path  12   b,  which are opened in the side faces  12   c  and  12   d  of the flow control member  12 , on the first flow path  2   a  side with respect to the ring packing  10   a  restrain the flow volume of the fluid flowing in the third flow path  12   b.    
         [0083]     Namely, the flow volume of the fluid flowing in the third flow path  12   b  can be adjusted by the axial position of the flow control member  12  with respect to the ring packing  10   a.    
         [0084]     Notching depths of the V-shaped notch, from the one end  12   a,  in the both side faces  12   c  and  12   d  of the flow control member  12  are mutually different. As shown in  FIG. 2 , the notching depth in the front face  12   c  is deeper than the notching depth in the rear face  12   d.    
         [0085]     With this structure, when the flow control member  12  is moved to locate a branching part of the V-shaped notch in the ring packing  10   a  so as to reduce the flow volume of the fluid in the third flow path  12   b,  the branching part in the rear face  12   d  is closed by the ring packing  10   a,  so that the first flow path  2   a  and the second flow path  2   b  are not mutually communicated; the first flow path  2   a  and the second flow path  2   b  are mutually communicated via the branching part in the front face  12   c  only. Namely, the first flow path  2   a  and the second flow path  2   b  can be mutually communicated via the V-shaped notch in the front face  12   c  only, so that the flow volume of the fluid flowing in the third flow path  12   b  can be precisely controlled even if the flow volume is small.  
         [0086]     Next, a mechanism for axially moving the flow control member  12 , which includes operation means, e.g., knob  4 , will be explained.  
         [0087]     As shown in  FIG. 2 , projected sections  12   g  are formed in the other end  12   e  part of the flow control member  12 , which is located in the first flow path  12   a.  The projected sections  12   g  respectively have second screw sections  12   f,  which are radially extended with respect to the axial line of the flow control member  12  until reaching the inner circumferential face of the knob  4  via the through-holes  2   c  and  2   d  of the main body  2  and which are screwed with the first screw section  4   a  of the knob  4 .  
         [0088]     Each of the projected sections  12   g  is constituted by a first part  12   ga  (see  FIG. 6 ), which is integrated with the flow control member  12 , and a second part  12   gb  (see  FIG. 7 ), which has an insert section  12   i  fitted in a hole  12   h  formed in an end face of the first part  12   ga.  By fitting the insert section  12   i  into the hole  12   h,  the second part  12   gb  is attached to the first part  12   ga.  The second screw section  12   f,  which is screwed with the first screw section  4   a  of the knob  4 , is formed in the second part  12   gb.    
         [0089]     The flow controller S 1  can be easily assembled by inserting the flow control member  12 , to which no second parts  12   gb  are attached, into the main body  2  and fitting the insert sections  12   i  of the second part  12   gb  into the holes  12   h  via the through-holes  2   c  and  2   d  of the main body  2 .  
         [0090]     By manually turning the knob  4 , the first and second screw sections  4   a  and  12   f  move the flow control member  12  in the axial direction.  
         [0091]     Note that, the projected sections  12   g  are introduced through the through-holes  2   c  and  2   d.  With this structure, when the knob  4  is turned with respect to the main body  2 , the projected sections  12   g  are engaged with edges of the through-holes  2   c  and  2   d.  Therefore, the flow control member  12  is not turned, with respect to the main body  2 , together with the knob  4 . The projected sections  12   g,  which are introduced through the through-holes  2   c  and  2   d  of the main body  2 , prevents the flow control member  12  from rotation.  
       Second Embodiment  
       [0092]     A second embodiment will be explained. Note that, the structural elements explained in the first embodiment are assigned the same symbols and explanation will be omitted.  
         [0093]      FIG. 8  is a perspective view of a flow controller S 2  of the second embodiment; and  FIG. 9  is a sectional view of the flow controller showing its inner mechanism.  
         [0094]     A main body  3  of the flow controller S 2  is constituted by a T-shaped pipe (see  FIG. 10 ).  
         [0095]     As shown in  FIG. 8 , a knob  5 , which can be manually turned, the first nipple member  6  having the first port  6   a  and the second nipple member  8  having the second port  8   a  are respectively provided to ends of the T-shaped main body  3 . The nipple members  6  and  8  are arranged so as to orthogonally cross the axial lines of the first port  6   a  and the second port  8   a.  In the second embodiment, the second nipple member  8  is provided to the lower end of the vertical section of the T-shaped pipe; the knob  5  and the first nipple member  6  are respectively provided to the ends of the horizontal section of the T-shaped pipe.  
         [0096]     As shown in  FIG. 9 , a first flow path  3   a,  which is communicated to the first port  6   a,  and a second flow path  3   b,  which is communicated to the second port  8   a,  are formed in the main body  3 .  
         [0097]     The circular projection  2   g,  the fourth flow paths  2   h  and the rubber member  10  including the ring packing  10   a  and the valve body  10   b  are provided as well as the first embodiment.  
         [0098]     A hollow rod-shaped flow control member  13  is provided in the main body  3 . The flow control member  13  is tightly pierced through the ring packing  10   a  and capable of relatively moving, in the axial direction, with respect to the ring packing  10   a.  While moving the flow control member  13 , an outer circumferential face of the flow control member  13  tightly contacts an inner circumferential face of the ring packing  10   a,  as well as the first embodiment.  
         [0099]     The flow control member  13  has a third flow path  13   b,  which is opened in one end face  13   a  and the outer circumferential face thereof and which makes the first flow path  3   a  communicate to the second flow path  3   b  via the ring packing  10   a.  Flow volume of the fluid flowing in the third flow path  13   b  can be controlled by adjusting the relative axial position of the flow control member  13  with respect to the ring packing  10   a.    
         [0100]     A bifurcated notch (an opening section) is formed in the one end  13   a  part of the flow control member  13 . The bifurcated notch is opened in the one end face  13   a  and the outer circumferential face of the flow control member  13  as a V-shaped notch. By forming the bifurcated (V-shaped) notch, the one end  13   a  part of the flow control member  13  is formed into a V-shape (see  FIGS. 9 and 12 ). The space in the V-shape acts as the third flow path  13   b.    
         [0101]     In the first embodiment, the one end  12   a  part of the flow control member  12 , in which the V-shaped notch is formed, is headed toward the second flow path  2   b.  On the other hand, in the second embodiment, the one end  13   a  part of the flow control member  13 , in which the V-shaped notch is formed, is headed toward the first flow path  3   a.  Note that, the one end  13   a  part may be headed toward the second flow path  3   b.  Namely, the one end  13   a  part, in which the V-shaped notch is formed, may be optionally headed toward the first flow path  3   a  or second flow path  3   b.    
         [0102]     As shown in  FIGS. 9 and 12 , the width of the third flow path  13   b  or the V-shaped notch (the opening section) is gradually increased toward the one end  13   a.  Namely, the width of the third flow path  13   b  in the circumferential direction of the flow control member  13  is gradually increased toward the one end  13   a.    
         [0103]     The flow volume of the fluid flowing in the third flow path  13   b  can be adjusted by varying area of the third flow path  13   b  opened in the side face of the flow control member  13 , which is located on the second flow path  3   b  side with respect to the ring packing  10   a.  The area of the third flow path  13   b  opened in the side face is varied by the axial position of the flow control member  13  with respect to the ring packing  10   a.    
         [0104]     Notching depths of the V-shaped notch, from the one end  13   a,  in the both side faces of the flow control member  13  are mutually different as well as the first embodiment.  
         [0105]     With this structure, when the flow control member  13  is moved to locate the branching part of the V-shaped notch in the ring packing  10   a,  the first flow path  3   a  and the second flow path  3   b  are mutually communicated via the V-shaped notch in one side face only, so that the flow volume of the fluid passing through the third flow path  13   b  can be precisely controlled, as well as the first embodiment, even if the flow volume is small.  
         [0106]     Next, a mechanism for axially moving the flow control member  13 , which includes the operation means, e.g., knob  5 , will be explained.  
         [0107]     As shown in  FIG. 12 , projected sections  13   j  are formed in the other end  13   e  part of the flow control member  13 . The projected sections  13   j  are radially extended, with respect to the axial line of the flow control member  13 , from the both side faces of the flow control member  13 .  
         [0108]     Further, as shown in  FIG. 9 , a cylindrical stopper  16  is provided in the main body  3 , more precisely provided in the end part of the main body  3 , to which the knob  5  will be attached. The stopper  16  is coaxially arranged with the main body  3 , so an outer circumferential face  16  is arranged along an inner circumferential face of the main body  3 . As shown in  FIGS. 13A and 13B , projected sections  16   e  are formed on the outer circumferential face of the stopper  16  and extended in the axial direction thereof. On the other hand, recesses, which are capable of respectively engaging with the projected sections  16   e,  are formed in the inner circumferential face of the main body  3 . With this structure, the stopper  16  cannot be turned with respect to the main body  3 . The stopper  16  has guide notches  16   a,  in which the projected sections  13   j  of the flow control member  13  will be respectively fitted (see  FIG. 13A ). With this structure, the flow control member  13  can be moved in the axial direction. Further, the stopper  16  has a notch  16   b  so as not to obstruct the flow of the fluid in the second flow path  3   b.    
         [0109]     As shown in  FIG. 9 , an engage section  16   c  of the stopper  16  is engaged with an engage section  5   b  of the knob  5 , which is formed like a circumferential groove, so that the knob  5  is rotatably retained.  
         [0110]     The one end  13   a  of the flow control member  13  is headed for the first port  6   a.  A bolt  14  is provided to the other end  13   e  of the flow control member  13 . The bolt  14  is coaxially arranged with the flow control member  13  as a first screw section  13   f.  Nuts  18  and  19  are provided to the knob  5  as second screw sections  5   a  screwed with the first screw section  13   f.    
         [0111]     A plurality of recesses  5   c  are formed in an inner face of the knob  5  (see  FIG. 11 ) and arranged in the circumferential direction. Projections  16   c,  which can engage with the recesses  5   c,  are formed in one end face of the stopper  16 , which faces the recesses  5   c  (see  FIG. 13B ). When the user turns the knob  5 , the projections  16   d  run on the recesses  5   c.  On the other hand, when the user stops turning the knob  5  at an optional rotational position, the projections  16   d  engages with the recesses  5   c,  so that the knob  5  can be retained at that position.  
         [0112]     With the above described structure, by manually turning the knob  5 , the first and second screw sections  13   f  and  5   a  move the flow control member  13  in the axial direction thereof.  
         [0113]     At that time, the projected sections  13   j  have fitted in the guide notches  16   a  of the stopper  16 . Therefore, the flow control member  13  is not turned together with the knob  5  when the knob  5  is manually turned. Namely, the projected sections  13   j  and the guide notches  16   a  of the stopper  16  prevent the flow control member  13  from rotation.  
         [0114]     In each of the flow controllers S 1  and S 2 , the fluid flows form the first port  6   a  to the second port  8   a  via the fourth flow paths  2   h  as free flow. On the other hand, the fluid flows form the second port  8   a  to the first port  6   a  via the third flow path  12   b  or  13   b  as controlled flow, whose flow volume is controlled by changing the axial position of the flow control member  12  or  13 . Unlike the conventional flow controller, each of the flow controllers S 1  and S 2  is capable of precisely controlling flow volume of the fluid with the unique flow control member  12  or  13  even if the flow volume is small.  
         [0115]     The flow volume is controlled by the third flow path  12   b  or  13   b,  which is opened in the outer circumferential face of the rod-shaped flow control member  12  or  13 , and the ring packing  10   a.  Namely, the flow controller S 1  and S 2  has no weak member, e.g., the needle of the conventional flow controller, so that the flow control members  12  and  13  are not badly damaged by fluid resistance. Therefore, the parts of the flow control members  12  and  13  can be composed of a light and inexpensive material, e.g., plastic.  
         [0116]     Note that, the present invention is not limited to the above described embodiments. Various modifications can be allowed.  
         [0117]     The third flow path formed in the flow control member must be opened in at least the outer circumferential face of the flow control member, and the flow volume of the fluid passing through the third flow path must be controlled according to the relative position of the flow control member with respect to the ring packing. For example, a flow control member  20  shown in  FIG. 14  may be employed. The flow control member  20  has a groove-shaped third flow path  20   b.  A circumferential width of an end of the third flow path  20   b,  which is opened in the outer circumferential face of the flow control member  20 , is gradually increased toward one end  20   a  of the flow control member  20 .  
         [0118]     In the present invention, the flow control member need not be moved in the axial direction with respect to the ring packing. The ring packing may be moved with respect to the flow control member. Further, both of the flow control member and the ring packing may be moved.  
         [0119]     The ring packing and the valve body need not be integrated. They may be separately provided.  
         [0120]     The invention may be embodied in other specific forms without departing from the spirit of essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.