Abstract:
In this valve structure, in a state in which a reciprocating member moves towards the seat surface, a valve body moves to the position where the valve unit sits on the valve seat, and with the movement of the reciprocating member in the direction away from the seat surface, the valve body moves in the direction in which the valve unit moves away from the valve seat. The valve structure includes a seal member that has a seal lip slidably contacting the surface of the valve body. The valve body has a separating unit which separates from the seal lip to form a gap between the valve body and the seal lip, and the separating unit is configured such that the amount of fluid passing through the gap between the valve body and the seal lip increases as the valve unit moves away from the valve seat.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a National Stage of International Application No. PCT/JP2013/082005, filed Nov. 28, 2013, which claims priority to Japanese Patent Application No. 2012-279221, filed Dec. 21, 2012. The entire disclosures of each of the above applications are incorporated herein by reference. 
     
    
     FIELD 
       [0002]    The present disclosure relates to a valve structure. 
       BACKGROUND 
       [0003]    Conventionally, solenoid valves have been widely used to control a flow rate and a fluid pressure corresponding to the flow rate. Some known solenoid valves use a linear solenoid configured such that the flow rate becomes proportional to an amount of current through a coil. A solenoid valve according to a conventional example using the linear solenoid is described by referring to  FIGS. 11 to 13 .  FIG. 11  is a schematic sectional view of a solenoid valve according to a conventional example in a state where a valve is closed in a portion around a valve section.  FIG. 12  is a schematic sectional view of the conventional solenoid valve in a state where the valve is opened in the portion around the valve section.  FIG. 13  is a graph showing a relationship between a flow rate and an amount of current through a coil of the conventional solenoid valve. 
         [0004]    In the solenoid valve according to the conventional example, a valve body section  120  and a rod  100  are integrally formed. The rod  100  reciprocates in accordance with the amount of current through the coil. The valve body section  120  protrudes from the center of a distal end surface  110  of the rod  100  in a distal end direction. An O ring  300  made of rubber is mounted on an outer circumference of the valve body section  120 . A valve seat  200  is provided with a valve hole  210 . 
         [0005]    According to the configuration described above, in a state where no current is flowing through the coil, the valve body section  120  of the rod  100  is disposed in the valve hole  210  of the valve seat  200 , and the O ring  300  is sandwiched between the distal end surface  110  of the rod  100  and a seat surface  220  of the valve seat  200 . Thus, the valve hole  210  is closed by the valve body section  120  and the O ring  300  (see  FIG. 11 ). When a current flows through the coil, the rod  100  moves in a direction in which the distal end surface  110  of the rod  100  moves away from the seat surface  220 . As a result, the valve body section  120  is pulled out from the valve hole  210  and the O ring  300  is separated from the seat surface  220 , whereby the valve hole  210  is opened (see  FIG. 12 ). 
         [0006]    Here, the O ring  300  made of rubber has viscosity. In the conventional example described above, the O ring  300  is sandwiched by the distal end surface  110  of the rod  100  and the seat surface  220  of the valve seat  200 . Thus, the O ring  300  is adhered to the seat surface  220  and deforms as follows. Specifically, the O ring  300  slightly expands in an axial direction right after the rod  100  starts to move from the state where the valve is closed, and then returns to the original shape upon being separated from the seat surface  220 . An O ring  300   a , illustrated with a dotted line in  FIG. 12 , shows the state of being expanded in the axial direction due to the adhesion to the seat surface  220 . Thus, as shown in a portion X in the graph of  FIG. 13 , the flow rate of a fluid temporarily increases right after the current starts to flow. In  FIG. 13 , L 1  shows how a current value increases from a state where no current is flowing, and L 2  shows how the current value reduces from a state where the current value is high to the state where no current is flowing. As shown in the graph, the flow rate is different between L 1  and L 2  with the same current value. This difference in flow rate is known as hysteresis. It can be understood that a larger hysteresis leads to a larger error of the flow rate with respect to a certain amount of current. One possible cause of the hysteresis is the problem due to the adhesion of the O ring  300  described above. 
         [0007]    The adhesion of the O ring  300  to the seat surface  200  and the resultant unstable (random) deformation described above causes the following problems. Specifically, a flow rate control becomes unstable right after the current starts to flow (the valve starts to open), and furthermore, the hysteresis increases to make the flow rate control less accurate. In the above description, the problem of a valve structure in the solenoid valve is described. A similar problem might occur in a valve structure of a valve using a driving source (such as a pneumatic actuator, a hydraulic actuator, or a piezoelectric actuator) other than a solenoid. 
       [Patent Document 1] Japanese Patent Application Laid-open No. 2006-226352 
       [0008]    [Patent Document 2] Japanese Examined Utility Model Application Publication No. H3-29645 
       SUMMARY 
       [0009]    An object of the present disclosure is to provide a valve structure that achieves more accurate flow rate control. 
         [0010]    The present disclosure has employed the following means for solving the problem. 
         [0011]    Specifically, a valve structure includes: a valve body disposed at a distal end of a reciprocating member configured to reciprocate by a reciprocation actuator; and a valve seat having a valve hole that closes when a valve portion of the valve body is seated on a seat surface of the valve seat and that opens when the valve portion is separated from the seat surface, the valve structure being configured such that, in a state where the reciprocating member moves toward the seat surface, the valve body moves to a position in which the valve portion is seated on the valve seat, and when the reciprocating member moves in a direction away from the seat surface, the valve body moves in a direction in which the valve portion is separated from the valve seat, the valve structure further including a seal member including a seal lip that contacts a surface of the valve body in a slidable manner, wherein the valve body includes a separation section that is separated from the seal lip so that a gap is formed between the valve body and the seal lip, after the valve portion is separated from the valve seat, and the separation section is configured such that a flow rate of a fluid passing through the gap between the valve body and the seal lip increases as the valve portion moves away from the valve seat. 
         [0012]    In the present disclosure, when the valve section of the valve body is seated on the valve seat, the seal lip of the seal member is in close contact with the surface of the valve body. Thus, a state is achieved where the seal lip and the valve section of the valve body work together to prevent the leakage of the fluid from the valve hole. Then, from the state where the valve is closed, the valve body moves in the direction in which the valve portion moves away from the valve seat. Thus, the fluid flows by passing between the seal lip and the valve body through the gap formed by the separation section formed on the valve body. The flow rate of the fluid passing through the gap increases as the valve section moves away from the valve seat. 
         [0013]    The present disclosure uses the seal member including the seal lip that contacts the surface of the valve body in a slidable manner, as the member that works together with the valve portion to prevent leakage of a fluid through the valve hole. When the valve body moves from a valve closed position, the area on the side closer to the valve hole and the area opposite thereto across the seal lip can communicate with each other through the gap formed by the separation section of the valve body, whereby the pressure difference between the areas gradually decreases. Thus, in the present disclosure, the separation of the valve portion of the valve body is facilitated compared with a case of an O ring of a conventional example that is separated from a seat surface from a state of being compressed from both sides. Furthermore, in the present disclosure, the flow rate of the fluid passing through the gap by the separation section between the valve body and the seal lip increases as the valve portion moves away from the valve seat. All things considered, the fluid control can be stably performed right after the valve starts to open. Furthermore, the separation of the valve portion from the seat surface is facilitated, whereby the error in the flow rate control due to hysteresis can be reduced. 
         [0014]    The separation section may be a tapered surface section formed in an area that faces the seal lip when the valve portion is separated from the valve seat, in a surface area in a range that faces the seal lip when the valve body reciprocates, and the tapered surface section may have a diameter reducing as the valve portion moves away from the valve seat, to be separated from the seal lip. 
         [0015]    Alternatively, the separation section may be a groove formed in an area on which the seal lip slides when the valve portion is separated from the valve seat, in a surface area in a range in which the seal lip slides when the valve body reciprocates, and the groove may be configured such that a flow rate of a fluid passing through a portion of contact between the valve body and the seal lip increases as the valve portion moves away from the valve seat. 
         [0016]    With the separation unit having the configuration described above, a stable fluid control can be achieved with a simple configuration. 
         [0017]    As described above, the present disclosure can achieve more accurate flow rate control. 
     
    
     
       DRAWINGS 
         [0018]      FIG. 1  is a schematic sectional view of a solenoid valve according to a first embodiment of the present disclosure. 
           [0019]      FIG. 2  is a schematic sectional view of a portion around a valve section in a state where a valve is closed, in the solenoid valve according to the first embodiment of the present disclosure. 
           [0020]      FIG. 3  is a schematic sectional view of the portion around the valve section in a state where the valve is opened, in the solenoid valve according to the first embodiment of the present disclosure. 
           [0021]      FIG. 4  is a schematic sectional view of a portion around a valve section in a state where a valve is closed, in the solenoid valve according to a second embodiment of the present disclosure. 
           [0022]      FIG. 5  is a schematic sectional view of the portion around the valve section in a state where the valve is opened, in the solenoid valve according to the second embodiment of the present disclosure. 
           [0023]      FIG. 6  is a schematic sectional view of the portion around the valve section in a state where the valve is closed, in the solenoid valve according to the second embodiment of the present disclosure. 
           [0024]      FIG. 7  is a schematic sectional view of a solenoid valve according to a third embodiment of the present disclosure. 
           [0025]      FIG. 8  is a schematic sectional view of a portion around a valve section in a state where a valve is closed, in the solenoid valve according to the third embodiment of the present disclosure. 
           [0026]      FIG. 9  is a schematic sectional view of the portion around the valve section in a state where the valve is opened, in the solenoid valve according to the third embodiment of the present disclosure. 
           [0027]      FIG. 10  is a diagram showing a sectional shape of a groove of a valve body in the solenoid valve according to the third embodiment of the present disclosure. 
           [0028]      FIG. 11  is a schematic sectional view of a portion around a valve section in a state where a valve is closed, in the solenoid valve according to a conventional example. 
           [0029]      FIG. 12  is a schematic sectional view of a portion around a valve section in a state where a valve is opened, in the solenoid valve according to the conventional example. 
           [0030]      FIG. 13  is a graph showing a relationship between an amount of current through a coil and a flow rate, in the solenoid valve according to the conventional example. 
       
    
    
     DETAILED DESCRIPTION 
       [0031]    Modes for carrying out the present disclosure will be exemplary described in detail based on embodiments, by referring to the drawings. There is no intension to limit the scope of present disclosure to the sizes, materials, shapes, and relative arrangement of components described in the embodiments, unless specifically noted. In the description below, a solenoid valve is described as an example of a device to which a valve structure is applied. 
       First Embodiment 
       [0032]    A solenoid valve according to a first embodiment of the present disclosure is described by referring to  FIGS. 1 to 3 . 
       &lt;Overall Configuration of Solenoid Valve&gt; 
       [0033]    An overall configuration of the solenoid valve according to the embodiment of the present disclosure is described by referring to  FIG. 1 . A solenoid valve SV includes a solenoid section S as an actuator for reciprocation, a valve section V as a valve structure, and a housing section H accommodating various components of the solenoid section S and the valve section V. 
         [0034]    The solenoid section S includes a bobbin  11 , a coil  12 , and a plunger  13 . The coil  12  is wound around the bobbin  11  and generates a magnetic field when a current flows through the coil  12 . The plunger  13  is a reciprocating member that is magnetically attracted to a center post  14  when a magnetic circuit is formed by the magnetic field generated by the coil  12 . The solenoid section S further includes a pair of plates  15   a  and  15   b  and a casing  15   c  all made of a magnetic material, for forming the magnetic circuit described above. The solenoid section S further includes a spring  16   a , a spring holder  16   b , and an adjust screw  16   c . The spring  16   a  biases the plunger  13  in a direction in which the plunger  13  moves away from the center post  14 . The spring holder  16   b  holds the spring  16   a . The adjust screw  16   c  adjusts the position of the spring holder  16   b . The solenoid section S further includes a terminal  17  electrically connected to the coil  12 . 
         [0035]    The housing section H includes a housing main body  21 , a cover  22 , and a reinforcement member  23 . The housing main body  21  accommodates the various components of the solenoid section S and the valve section V. The cover  22  is fixed to the housing main body  21 . The reinforcement member  23  reinforces the housing main body  21 . The housing main body  21  includes an input port section  21   a , in which a fluid flows from a source pressure side, and an output port section  21   b , through which the fluid is discharged to an output side (control pressure side). The housing main body  21  further includes a connector section  21   c  used for electrical connection to receive power supply from an outer power source. 
         [0036]    The valve section V includes a valve body  30  and a valve seat  40 . The valve body  30  is disposed at a distal end of the plunger  13 . The valve is closed or opened when the valve body  30  is seated on or is separated from the valve seat  40 . The valve section V further includes a seal member  50  that seals the fluid failed to be prevented from leaking by a valve portion of the valve body  30 . The valve section V further includes an annular supporting member  60  that supports the valve seat  40  and the seal member  50 . The valve section V further includes a seal ring  61  and a supporting member  70 . The seal ring  61  seals a gap between an outer circumference surface of the supporting member  60  and an inner circumference surface of the housing main body  21 . The supporting member  70  supports the valve seat  40  and the supporting member  60 . 
         [0037]    The adjust screw  16   c  adjusts the position of the spring holder  16   b  so that the flow rate (or a fluid pressure corresponding to the flow rate) is controlled as desired by a balance between a biasing force of the spring  16   a  described above and a magnetic force corresponding to the amount of current through the coil  12 . 
       &lt;Valve Section (Valve Structure)&gt; 
     &lt;&lt;Configuration of Valve Section&gt;&gt; 
       [0038]    The configuration of the valve section V is described more in detail by mainly referring to  FIGS. 2 and 3 . As described above, the valve section V includes the valve body  30 , the valve seat  40 , the seal member  50 , and the supporting member  60 . 
         [0039]    The valve body  30  is a substantially column shaped member, and has one end fixed to the plunger  13  and an end surface on the other end serving as a valve portion  31 . The valve body  30  reciprocates together with the plunger  13 , when the current flows through the coil  12 . 
         [0040]    The valve seat  40  is an annular member, and is provided with a valve hole  41  (through hole) at the center. An end surface area, around the valve hole  41  and on the side of the plunger  13 , serves as a seat surface  42  of the valve seat  40 . A state where the valve hole  41  is closed (valve closed state) is achieved, when the valve portion  31  as the end surface of the valve body  30  comes into contact with the seat surface  42 . The center axes of the valve body  30  and the valve hole  41  substantially match, and the valve body  30  has a larger diameter than the valve hole  41 . 
         [0041]    The seal member  50  is a member for sealing the fluid failed to be prevented from leaking by the valve portion  31  of the valve body  30 , that is a fluid leaked out through a gap between the seated valve portion  31  and the valve seat  42 . The seal member  50  includes a seal lip  51  that contacts an outer circumference surface of the valve body  30  in a slidable manner. The seal member  50  has substantially a configuration in which a rubber elastic body  53  is baked and thus is fixed on a metal ring  52  as an annular reinforcement member, and the outer circumference surface of the seal member is fitted in the inner surface of the supporting member  60 . The reinforcement member may be any rigid member, and may be made of, for example, a material other than metal such as resin. The metal ring  52  includes a tubular section  52   a  and a flange section  52   b  and has a substantially L shaped semi-cross section. The flange section  52   b  extends radially inward from one end of the tubular section  52   a . The seal lip  51  serves as a part of the rubber elastic body section  53 , and protrudes from the distal end section of the flange section  52   b  in a direction, in which the valve body  30  moves toward the valve seat  40 , while being bent radially inward with respect to the axial direction. The diameter of the distal end section of the seal lip  51  is set to be smaller than a diameter of the valve body  30  (the diameter of the contacted area in the valve closed state). Thus, an interface or interference margin is provided between the seal lip  51  and the valve body  30 . The rubber elastic body section  53  may be made of a material such as, for example, polyurethane, nitrile butadiene rubber (NBR), hydrogenated nitrile butadiene rubber (HNBR), or fluorocarbon rubber (FKM). The configuration of the seal member  50  is not particularly limited, and thus the configuration described above is merely an example. Any other conventionally known seal for reciprocation may be used as appropriate. 
         [0042]    The valve body  30  is provided with a tapered surface section  32  as a separation section, at a part of the outer circumference surface. The tapered surface section  32  is formed in an area, of the outer circumference surface of the valve body  30 , that faces the seal lip  51  when the valve body  30  reciprocates, excluding an area that faces (is in contact with) the seal lip  51  when the valve portion  31  is seated on the valve seat  42 . Specifically, the tapered surface section  32  is formed in an area that faces the seal lip  51  when the valve portion  31  is separated from the valve seat  42 . The tapered surface section  32  is formed to have a tapered shape in which the diameter decreases toward the valve portion  31  at the distal end of the valve body  30 . 
       &lt;&lt;Mechanism of Valve Section&gt;&gt; 
       [0043]    A mechanism of the valve section V is described by mainly referring to  FIGS. 2 and 3 . 
         [0044]    When no current is flowing through the coil  12  of the solenoid section S, no magnetic force is produced. Thus, the plunger  13  is moved away from the center post  14  by the biasing force from the spring  16   a . Thus, as shown in  FIG. 2 , the valve portion  31  of the valve body  30  is seated on the seat surface  42  of the valve seat  40 , whereby the valve is closed. Here, the seal lip  51  of the seal member  50  is in close contact with the outer circumference surface of the valve body  30 , outside the area where the tapered surface section  32  is formed. Thus, as shown in  FIG. 2 , a strip shaped seal region R where the seal lip  51  is in contact with the entire outer circumference surface of the valve body  30  is formed. The seal range R is a portion of contact between. Thus, a flow path from the input port section  21   a  to the output port section  21   b  is blocked at two stages, that is, by the adhesion between the valve portion  31  and the seat surface  42  and by the seal region R formed by the seal member  50 . 
         [0045]    As the amount of current through the coil  12  of the solenoid section S increases, the magnetic attraction force increases. Thus, the plunger  13  moves toward the center post  14  against the biasing force from the spring  16   a , whereby the valve body  30 , disposed at the distal end of the plunger  13 , also moves toward the center post  14 . As a result, the valve portion  31  of the valve body  30  is separated from the seat surface  42  of the valve seat  40 . The position of the seal region R, as the portion of contact between the valve body  30  and the seal lip  51 , also moves from a seal position where the seal lip  51  contacts the entire circumference of the outer circumference surface of the valve body  30 , to the area where the tapered surface section  32  is formed. Once the diameter of the tapered surface section  32  becomes smaller than an inner diameter of the seal lip  51 , that is, once the interface or interference margin between the seal lip  51  and the tapered surface section  32  is lost, a gap is formed between the valve portion  31  and the seat surface  42 . Thus, a flow path is formed that passes through the outer circumference surface side of the valve portion  31 , and between the tapered surface section  32  and the seal lip  51 , from the valve hole  41  (see the arrow A in  FIG. 3 ). Thus, the fluid flowed in through the input port section  21   a  is discharged through the output port section  21   b . The position of the valve body  30  disposed at the distal end of the plunger  13 , and the resultant size of the gap between the valve portion  31  and the seat surface  42 , are determined in accordance with the amount of current through the coil  12 . Thus, the flow rate and the fluid pressure of the fluid discharged through the output port section  21   b  can be controlled by controlling the amount of current through the coil  12 . 
       Second Embodiment 
       [0046]    A solenoid valve according to a second embodiment of the present disclosure will be described by referring to  FIGS. 4 to 6 . Here, the difference from the first embodiment will be mainly described. The components that are the same as the counterparts in the first embodiment will be denoted with the same reference signs and will not be described. Matters not particularly described in this embodiment are the same as the counterparts in the first embodiment. 
         [0047]    The solenoid valve according to this embodiment has the following configuration. The seal member  50  is mounted on the supporting member  60  in an opposite direction from that in the first embodiment. Specifically, the seal lip  51  protrudes from the distal end of the flange section  52   b  in a direction in which the valve body  30  moves away from the valve seat  40 , while being bent radially inward with respect to the axial direction. 
         [0048]    As shown in  FIG. 6 , this embodiment provides a configuration of facilitating the separation of the seal lip  51  from the valve body  30  through deformation, by the pressure (source pressure) of the fluid flowing in through the input port section  21   a . This deformed state is illustrated by the dashed line in  FIG. 6 . In a case of the solenoid valve with a high source pressure setting, the sealing property is of a great importance, and thus the configuration in the first embodiment, in which the seal lip  51  is bent toward a sealing fluid side, is preferable, while in a case of the solenoid valve with a low source pressure setting, the configuration of the second embodiment can be used. With the configuration of this embodiment, the discharges flow rate can be increased when desired by the deformation of the seal lip  51  in the low source pressure setting. 
       Third Embodiment 
       [0049]    A solenoid valve according to a third embodiment of the present disclosure will be described by referring to  FIGS. 7 to 9 . Here, the difference from the embodiments described above will be mainly described. The components that are the same as the counterparts in the embodiments described above will be denoted with the same reference signs and will not be described. Matters not particularly described in this embodiment are the same as the counterparts in the embodiments described above. 
         [0050]    In this embodiment, grooves  33 , as a separation section, are formed on the outer circumference surface of the valve body  30 . The grooves  33  are formed in an area of the outer circumference surface of the valve body  30  where the seal lip  51  slides along with the reciprocation of the valve body  30 , excluding an area in contact with the seal lip  51  when the valve portion  31  is seated on the valve seat  42 . Specifically, the grooves  33  are formed in an area on which the seal lip  51  slides after the valve portion  31  is separated from the valve seat  42 . The groove  33  extends on the outer circumference surface of the valve body  30 , in a direction in which the valve body  30  reciprocates. The depth of the groove is the largest on the side of the valve portion  31 , and is smaller at a portion farther from the valve portion  31 . The groove  33  has a substantially isosceles triangular opening shape in the axial direction, and thus the groove width is the largest at the side of the valve portion  31 , and reduces as it moves away from the valve portion  31 . 
         [0051]    When no current is flowing through the coil  12  of the solenoid section S, no magnetic force is produced. Thus, the plunger  13  is moved away from the center post  14  by the biasing force from the spring  16   a . Thus, as shown in  FIG. 8 , the valve portion  31  of the valve body  30  is seated on the seat surface  42  of the valve seat  40 , whereby the valve is closed. Here, the seal lip  51  of the seal member  50  is in close contact with the outer circumference surface of the valve body  30 , outside the area where the groove  33  is formed. Thus, as shown in  FIG. 8 , the strip shaped seal region R is formed. The seal region R is a portion of contact between the seal lip  51  and the entire circumference of the outer circumference surface of the valve body  30 . Thus, the flow path from the input port section  21   a  to the output port section  21   b  is blocked at two stages, that is, by the adhesion between the valve portion  31  and the seat surface  42  and by the seal region R formed by the seal member  50 . 
         [0052]    As the amount of current through the coil  12  of the solenoid section S increases, the magnetic attraction force increases. Thus, the plunger  13  moves toward the center post  14  against the biasing force from the spring  16   a , whereby the valve body  30 , disposed at the distal end of the plunger  13 , also moves toward the center post  14 . As a result, the valve portion  31  of the valve body  30  is separated from the seat surface  42  of the valve seat  40 . The position of the seal region R, as a portion of contact between the valve body  30  and the seal lip  51 , also moves from the seal position where the seal lip  51  contacts the entire circumference of the outer circumference surface of the valve body  30 , to the area where the grooves  33  are formed. Thus, the gap is formed between the valve portion  31  and the seat surface  42 , and a gap is further formed in the seal region R by the groove  33 . Thus, a flow path is formed that passes through the outer circumference surface side of the valve portion  31 , and between the groove  33  and the seal lip  51 , from the valve hole  41  (see the arrow A in  FIG. 9 ). Thus, the fluid flowed in through the input port section  21   a  is discharged through the output port section  21   b.    
       Advantage of Solenoid Valve According to the Embodiments 
       [0053]    In the solenoid valve SV according to the embodiments, the plunger  13  moves in the direction in which the valve portion  31  of the valve body  30  moves away from the seat surface  42  of the valve seat  40 , when the current starts to flow through the coil  12  from the state where no current is flowing through the coil  12 , and as the amount of current increases. In this process, the relative position between the valve body  30  and the seal member  50  changes, and also the position of the seal region R, as a portion of contact between the valve body  30  and the seal lip  51 , also moves from the seal position where the seal lip  51  contacts the entire circumference of the outer circumference surface of the valve body  30 , to the area where the tapered surface section  32  or the grooves  33  are formed ( FIG. 2  to  FIG. 3 ,  FIG. 4  to  FIG. 5 , and  FIG. 8  to  FIG. 9 ). 
         [0054]    The valve body  30  according to the embodiments employs the configuration of using the seal member  50 , as a seal for reciprocation, to seal the fluid failed to be prevented from leaking by the valve portion  31  of the valve body  30  alone. The seal lip  51  of the seal member  50  contacts the outer circumference surface of the valve body  30  in a slidable manner. Thus, the seal lip  51  is not unstably deformed, unlike the O ring in the conventional example, and can exert the sealing function without hindering the movement of the valve body  30 . 
         [0055]    Furthermore, in the embodiments, when the valve body  30  moves from the closing position, the fluid flows between the seal lip  51  and the valve body  30  through the gap formed by the tapered surface section  32  of the valve body  30  or the grooves  33  formed on the surface of the valve body  30 . The flow rate of the fluid passing through the gap increases as the valve portion  31  moves away from the valve seat  42 . As described above, the area on the side closer to the valve hole  41  and the area opposite thereto across the seal lip  51  can communicate with each other through the tapered surface section  32  or the grooves  33 . Thus, the pressure difference between the areas gradually reduces. Thus, the fluid control can be stably performed right after the current starts to flow (right after the valve starts to open). The separation of the valve portion  31  from the seat surface  42  is facilitated, whereby the error in the flow rate control due to hysteresis can be reduced. The O ring of the conventional example has the adhered state changing every time the plunger reciprocates, and thus causes the fluctuation of the fluid rate characteristics. Such a problem can be solved by the solenoid valve SV according to the embodiments, and thus the stable fluid rate characteristics can be achieved. 
         [0056]    The solenoid valve SV according to the embodiments has the configuration of elastically supporting the side of the valve body  30  where the valve portion  31  is disposed, by the seal lip  51  of the seal member  50 . Thus, the displacement of the center axis due to the reciprocation of the valve body  30  from the center axis of the valve seat  40  can be prevented. As a result, the accuracy of the seating position of the valve portion  31  of the valve body  30  on the seat surface  42  can be improved. 
         [0057]    In the solenoid valve SV according to the third embodiment, as described above, the groove  33  has the sectional shape increasing as the valve portion  31  moves away from the valve seat  42 . Thus, the area of the flow path, in which the fluid flows, gradually increases as the valve portion  31  moves away from the valve seat  42 . In the third embodiment, the groove  33  has the following configuration. Specifically, as shown in  FIGS. 8 and 9 , the depth changes along the center axis direction, and the opening has a substantially triangular shape (as viewed in a direction orthogonal to the center axis line). Thus, the flow path, through which the fluid flows, is not suddenly widened by the transition to the open valve state. By setting the shape, number, and arrangement of the grooves  33 , linear change of the flow rate with respect to the amount of current through the coil  12  can be achieved, and the maximum flow rate can be adjusted. The groove  33  may have various configurations. As shown in  FIG. 10 , the sectional shape of the groove  33  may be a substantially rectangular shape with no change in the groove width in the depth direction ( FIG. 10(   a )), a substantially triangular shape with the groove width changing in the depth direction ( FIG. 10(   b )), a substantially semicircular shape ( FIG. 10(   c )), or the like. The opening shape of the groove  33  is not limited to the substantially triangular shape as shown in  FIGS. 8 and 9 , and may be, for example, a substantially rectangular shape with no change in the groove width in the axial direction, a trapezoidal shape with a gently changing grove width, or the like. The number and the arrangement of the grooves  33  are not limited to those in  FIGS. 8 and 9 , in which the four grooves  33  are arranged at an equal interval. 
         [0058]    In the solenoid valve according to the third embodiment, the direction in which the seal member  50  is mounted on the supporting member  60 , may be opposite to that in the configuration described above. Specifically, in the configuration described above, the seal lip  51  protrudes from the distal end section of the flange section  52   b  in the direction, in which the valve body  30  moves away from the valve seat  40 , while being bent radially inward with respect to the axial direction, as shown in  FIGS. 7 to 9 . Alternatively, the seal member  50  may be mounted on the supporting member  60  in the following manner. Specifically, the seal lip  51  may protrude from the distal end section of the flange section  52   b  in which the valve body  30  moves towards the valve seat  40 , while being bent radially inward with respect to the axial direction. 
         [0059]    In the solenoid valve SV according to the embodiment, the level of the bending (diameter reduction) and the formed range of the tapered surface section, the settings of the size and the number of the grooves  33 , the configuration and the material of the seal member  50 , the interface or interference margin between the seal lip  51  and the valve body  30 , or the like may be set in such a manner that the flow rate with respect to a certain current value is less affected by the amount of the source pressure. Thus, even when the source pressure changes, the control pressure (pressure of the fluid discharged from the output port  21   b ) can be stabilized. 
         [0060]    In the embodiments described above, the configuration where the valve body  30  is disposed at the distal end of the plunger  13  is described. Alternatively, the present disclosure is applicable to the configuration, in which the valve body is disposed at a distal end of the rod disposed on the plunger. The embodiments described above are described with a case where the valve structure is applied to the solenoid valve as an example. Alternatively, the valve structure is applicable to the valve structure other than that of the solenoid valve. Thus, the reciprocation actuator for reciprocating the reciprocating member is not limited to the solenoid. Alternatively, a pneumatic actuator, a hydraulic actuator, and a piezoelectric actuator may be used. The present disclosure is applicable to a valve structure, in which a valve body is disposed in the reciprocating member that reciprocates by the various reciprocation actuators. 
       EXPLANATION OF REFERENCE NUMERALS 
       [0000]    
       
           11  bobbin 
           12  coil 
           13  plunger 
           13   a  fitting recess 
           14  center post 
           15   a ,  15   b  plate 
           15   c  casing 
           16   a  spring 
           16   c  adjust screw 
           17  terminal 
           21  housing main body 
           21   a  input port section 
           21   b  output port section 
           21   c  connector section 
           22  cover 
           23  reinforcement member 
           30  valve body 
           31  valve portion 
           32  tapered surface section (separation section) 
           33  groove (separation section) 
           40  valve seat 
           41  valve hole 
           42  seat surface 
           50  seal member 
           51  seal lip 
           52  metal ring 
           53  rubber elastic body section 
           60  supporting member 
           61  seal ring 
           70  supporting member 
         SV solenoid valve 
         H housing section 
         S solenoid section 
         V valve section