Patent Publication Number: US-2023136072-A1

Title: Valve and fluid control device

Description:
TECHNICAL FIELD 
     The present invention relates to a valve that accommodates therein a sensor inside of a machine and is able to output data detected by the sensor. 
     BACKGROUND ART 
     Conventionally, there are many valves equipped with sensors to confirm opening and closing operations of the valves. Among such valves, especially in the valve for integration, a sensor or an operation part is provided on an upper part or an upper surface of the valve so that an operation such as installation or removal of the valve, or an operation such as supply of driving pressure or driving operation can be performed from the upper part of the valve. In the case of such a design, the opening and closing operation of the valve is often detected by the vertical movement of a piston. 
     In this regard, for example, in Patent Literature 1, discloses an air operation valve for chemicals having a piston rod for opening or closing a valve by reciprocating within a valve body and an indication member connected to the piston rod and inserted into a penetration hole of the valve body, and provided with a detection switch for detecting a location of a tip part of the indication member and a case which covers the detection switch and the tip part of the indication member and is attached to the valve body. Further, in Patent Literature 2, an air operation valve provided with an actuator for raising and lowering a stem by supplying or interrupting a working fluid, and having an opening and closing detection sensor for detecting opening and closing of a valve body accompanying raising and lowering of a piston based on a change in a distance to the piston. 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: JP 2001-153261A 
     Patent Literature 2: JP 2021-025529A 
     SUMMARY OF INVENTION 
     Technical Problem 
     However, when the operation of the valve is detected in accordance with the operation of the piston for opening and closing the valve, if the piston is inclined, an object to be detected is inclined, and there is a possibility that detection failure occurs since accurate detection cannot be performed, and if displacement (stroke amount) of the piston is small, the detection accuracy may be further affected. 
     Therefore, one of the objects of the present invention is to provide a valve capable of accurately detecting the operation of the valve. 
     Solution to Problem 
     In order to achieve the above object(s), a valve according to the present invention includes a valve body defining a fluid flow passage, a valve disk operating to open and close the fluid flow passage, an actuator driving the valve disk by supplying or interrupting a working fluid, a stem transmitting a driving force of the actuator to the valve disk, a detection means detecting an opening and closing operation of the valve disk, and an elastic member fixing a ring-shaped magnetic body inserted through an end of the stem to the stem, wherein the detection means includes the magnetic body fixed by the elastic member, and a magnetic sensor detecting a change in a magnetic field of the magnetic body. 
     A recess may be provided along a circumferential direction on an outer peripheral surface of the stem fixed to the magnetic body, and an inclined part having a diameter expanding outward may be provided at an end of the recess. 
     The actuator may include an actuator cap storing a pressure chamber, to which a working fluid is supplied, inside, and protruding one end of the stem to an outside on a side opposite to the valve disk, and the valve may further include a sensor cap covering the detection means together with one end of the stem, and a bolt inserted into a bolt hole of the sensor cap is fastened to a fastening groove provided on an outer peripheral surface of the actuator cap. 
     An inclined part, having a diameter expanding outward, may be formed in a vicinity of the fastening groove. 
     The magnetic sensor may be attached to an outer surface of the actuator cap. 
     The magnetic sensor may be attached to an inside of the sensor cap. 
     It may be configured as a fluid control device including the above-described valve. 
     Effect of the Invention 
     According to the valve of the present invention, the operation of the valve can be detected with high accuracy. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is an external perspective view illustrating a valve according to an embodiment of the present invention. 
         FIG.  2    is a cross-sectional view illustrating an internal structure of a valve according to an embodiment of the present invention. 
         FIG.  3    is a partially enlarged cross-sectional view illustrating an internal structure of a valve according to an embodiment of the present invention. 
         FIG.  4    is an exploded perspective view illustrating a sensor unit of a valve according to an embodiment of the present. 
         FIG.  5    is a plan view of a sensor unit of a valve according to an embodiment of the present invention. 
         FIG.  6    is a partially enlarged cross-sectional view illustrating an internal structure of a valve according to an embodiment of the present invention. 
         FIG.  7 A  is a diagram illustrating a process to fasten a bolt when attaching a sensor cap to an actuator cap in a valve according to the present embodiment. 
         FIG.  7 B  is a diagram illustrating a process to fasten a bolt when attaching a sensor cap to an actuator cap in a valve according to the present embodiment. 
         FIG.  7 C  is a diagram illustrating a process to fasten a bolt when attaching a sensor cap to an actuator cap in a valve according to the present embodiment. 
         FIG.  8    is a cross-sectional view illustrating an internal structure of a valve according to another embodiment of the present invention. 
         FIG.  9    is an external perspective view illustrating an example of a fluid control device in which a plurality of valves according to the present embodiment are integrated. 
     
    
    
     PREFERRED EMBODIMENT 
     An embodiment of the present invention will be described below with reference to the drawings. According to one embodiment of the present invention,  FIG.  1    illustrates an external view of an air operation valve (hereinafter also referred to simply as a valve  1 ) having a sensor unit  5 , and  FIG.  2    illustrates a vertical cross section of the valve  1  when the valve is closed. In the following description, the directions of members and the like may be referred to as upper, lower, left, and right depending on the directions in the drawings for the sake of convenience, but these do not limit the directions of members or the like in the actual situation or an embodiment of the present invention. 
     The valve  1  is a metal diaphragm valve of a direct touch type, which is highly accurately controlling a microflow rate of a process fluid, and is provided with a valve body  2 , a diaphragm  30 , a bonnet  31 , a bonnet nut  32 , an actuator  4 , a sensor unit  5  and the like. The valve  1  is used, for example, in a semiconductor manufacturing apparatus using a film formation technique of an ALD (Atomic Layer Deposition) method. 
     Valve Body  2   
     The valve body  2  is a member made of a steel material such as stainless and defines a fluid flow passage. Two flow passage ports are provided in a lower part of the valve body  2 , and a fluid inflow passage  20  and a fluid outflow passage  21  are formed from the respective flow passage ports. A valve chamber  22  having a substantially concave cross section, which opens upward and communicates with the fluid inflow passage  20  and the fluid outflow passage  21 , is formed on an upper part of the valve body  2 . A synthetic resin valve seat  23  is provided on a bottom surface of the valve chamber  22 , and an annular stepped part  24  is formed on a lower side of an inner peripheral surface of the valve chamber  22 . 
     Diaphragm  30   
     The diaphragm  30  is a valve disk which operate to be able to open and close the fluid flow passage, has an extremely thin thickness, and is made of a metal material such as stainless steel or other shape memory alloys. This diaphragm  30  is arranged above the valve seat  23  and constituted of a plurality of diaphragms. Further, the diaphragm  30  has a dish-like shape in which a central part is curved upward in a natural state. 
     A retaining adapter  44  is an annular member attached to an inner peripheral surface of the valve chamber  22 , and is pressed toward the stepped part  24  by a cylindrical lower end part of the bonnet  31 . A peripheral edge of the diaphragm  30  is clamped and fixed by the stepped part  24  and the retaining adapter  44  so that an airtightness of the valve chamber  22  is maintained. 
     Bonnet  31   
     The bonnet  31  is formed in a substantially cylindrical shape with a lid, and a lower end of the cylindrical shape is inserted into the valve chamber  22  of the valve body  2  and threadedly engaged with an upper part of the cylindrical shape of the valve body  2 . A stem  40  is arranged in the bonnet  31 , and a coiled spring  42  is arranged around the stem  40 . The spring  42  downwardly biases an expanding diameter part  403  formed at a bottom of the stem  40 . At a bottom surface of the expanding diameter part  403 , a diaphragm retainer  43 , which is made of synthetic resin and is capable of being brought into contact with a top surface of a center part of the diaphragm  30 , is fitted. 
     Actuator  4   
     The actuator  4  is a fluid operated drive mechanism that elevates and lowers the stem  40  by supplying or interrupting the working fluid from a fluid supply source not shown in the figures. As a result, the diaphragm  30 , which is a valve disk, is brought into contact with or separate from the valve seat  23  to perform the opening and closing operation of the valve  1 . The actuator  4  includes a housing  45 , two pressure chambers  46  vertically partitioned in the housing  45 , two pistons  47  vertically arranged in the housing  45  facing the individual pressure chambers  46 , and one partitioning member  48  arranged between each of the pistons  47  in the housing  45 . In addition, the actuator  4  may include a stroke adjustment mechanism that can be able to adjust a stroke amount by elevating and lowering the stem  40 . 
       FIG.  3    illustrates an enlarged view of the actuator  4 . The housing  45  is formed by threadedly engaging to connect an upper side of an actuator cap  451  and a lower side of an actuator body  452 . 
     The actuator cap  451  stores the pressure chamber  46 , where the working fluid is supplied, inside of the actuator cap  451 , and protrudes one end of the stem  40  to an outside, an opposite side to the diaphragm  30 . In other words, a through hole  45   a  is formed in an upper part of the actuator cap  451  and the stem  40  is stored in the sensor unit  5  inserted into the through hole  45   a.  A flow passage  41  formed in the stem  40  includes an axial hole  41  a extending in an axial direction of the stem  40  and two routes of radial holes  41   b  diverging in a radial direction from the axial hole  41   a.  The working fluid is supplied to two pressure chambers  46  from a supply port  53   a  through the axial hole  41   a  and the radial holes  41   b  in this order. 
     An opening  45   d  to insert the stem  40  is formed in a lower part of the cylindrical shape  4521  of the actuator body  452 . By threadedly engaging the lower part of the cylindrical shape  4521  with the bonnet  31  and fastening a bonnet nut  32 , the actuator  4  is fastened and fixed to the bonnet  31 . The stem  40  is supported in the housing  45  to be able to elevate and lower. 
     Stem  40   
     The stem  40  includes a stem body  401  elevating and lowering in the bonnet  31 , and a rod  402  extending from the housing  45  of the actuator  4  to the sensor unit  5 , and their upper end and lower end threadedly engaged with each other. As a result, the stem body  401  and the rod  402  connected to each other integrally form the stem  40 , and elevate and lower in the bonnet  31 , the housing  45 , and the sensor unit  5 , which will be described later. 
     The rod  402  which forms the stem  40  is inserted to the through hole  45   a  formed in an upper surface of the actuator cap  451  and stored in the sensor unit  5 . The flow passage  41  of the working fluid is provided in the rod  402 , and this flow passage  41  communicates with the supply port  53   a  of the working fluid formed in an upper surface of a sensor cap  53 . As a result, the working fluid supplied from the fluid supply source flows into the flow passage  41  through the supply port  53   a.    
     Two pistons  47  are connected to the rod  402  constituting the stem  40  and stored in the housing  45  with the rod  402  to be able to elevate and lower. Each of the pistons  47  has a sliding outer peripheral surface  47   a,  a first pressure receiving surface  47   b,  and an inner peripheral surface  47   c.  The sliding outer peripheral surface  47   a  slides on an inner wall  45   e  of the housing  45  through an O-ring  61  as the stem  40  elevates and lowers. The first pressure receiving surface  47   b  has an annular shape, partitions the pressure chamber  46  together with the inner wall  45   e,  and receives a pressure of the working fluid. 
     Below the lower piston  47 , the pressure chamber  46  is partitioned with the first pressure receiving surface  47   b,  the inner wall  45   e,  and a bottom wall  45   f  of the housing  45  which is a part of the inner wall  45   e.  The inner peripheral surface  47   c  of the piston  47  is fixed to an outer peripheral surface  40   a  of the stem  40  through the O-ring  62  with an intermediate fitting rather than an interference fitting such as press-fitting. A first fitting part  471  is formed in the inner peripheral surface  47   c.    
     The stem  40  is provided with a flange part  404 . The flange part  404  is formed by enlarging the outer peripheral surface  40   a  of the stem  40 , and a lower surface  404   a  of the flange part  404  is in contact with an upper surface  47   d  of an upper side of the piston  47 . As a result, when the working fluid is supplied to the pressure chamber  46 , the stem  40  is pushed up with the piston  47  by pressures of each of the pressure chamber  46  to rise. 
     When the valve  1  is assembled, the O-ring  62  is fitted into the first fitting part  471  either before or after the piston  47  is connected to the stem  40 . Since the piston  47  is not press-fitted into the stem  40 , the O-ring  62  can be reliably prevented from damaged, entangled and broken, and a sealing function of each of the pressure chambers  46  can be achieved. 
     Further, a state of the O-ring  62  can be easily and visually confirmed from the first fitting part  471 . Therefore, even if the O-ring  62  is damaged, entangled or broken, these conditions can be detected at an early stage. Further, the O-ring  62  is fitted into the first fitting part  471  with friction while its own elastic force due to collapse and deformation acts on the inner wall of the first fitting part  471 . Therefore, the O-ring  62  does not fall off even when the piston  47  elevates and lowers. 
     Furthermore, since the O-ring  62  is exposed to the pressure chamber  46 , when the valve  1  is fully opened, the O-ring  62  is pressed against the inner wall of the first fitting part  471  by the pressure of the working fluid acting on the pressure chambers  46 . This pressing force further promotes collapse and deformation of the O-ring  62  in the first fitting part  471 , and further improves a sealing performance of each of the pressure chambers  46 . 
     In addition, the O-ring  62  may be exposed to the pressure chambers  46  and in contact with the working fluid, and may thermally expand in response to a temperature at which the working fluid is exposed. When such thermal expansion of the O-ring  62  occurs in a fitting groove with a limited space as in conventional cases, deterioration such as hardening, softening, swelling, and etc. of the O-ring  62  may occur since the thermal expansion is restricted and there is no place for heat to escape. 
     However, in the case of the present embodiment, the O-ring  62  is fitted into the first fitting part  471  to ensure a degree of freedom of thermal expansion to a certain extent and to secure an escape path of heat to a certain extent. Therefore, the deterioration of the O-ring  62  caused by the thermal expansion and influence on the sealing performance of the pressure chambers  46  are reduced. 
     The partitioning member  48  is fixed to the inner wall  45   e  between the two pistons  47 , and partitions an upper side of the pressure chambers  46  with the first pressure receiving surface  47   b  of the upper side of the piston  47  and the inner wall  45   e.  Specifically, the partitioning member  48  has a sliding inner peripheral surface  48   a,  a second pressure receiving surface  48   b,  and a fixed outer peripheral surface  48   c.  The sliding inner peripheral surface  48   a  slides on the outer peripheral surface  40   a  of the stem  40  through an  0 -ring  63  as the stem  40  elevates and lowers. 
     The second pressure receiving surface  48   b  has an annular shape, partitions the pressure chambers  46  together with the inner wall  45   e  and the first pressure receiving surface  47   b,  and receives the pressure of the working fluid. The fixed outer peripheral surface  48   c  is fixed to the inner wall  45   e  through the O-ring  63 . In the sliding inner peripheral surface  48   a,  the outer peripheral surface  40   a  of the stem  40  slides as the stem  40  elevates and lowers. Further, a second fitting part  481  is formed in the sliding inner peripheral surface  48   a.    
     The second fitting part  481  is formed by cutting off a corner part extending from the sliding inner peripheral surface  48   a  to the second pressure receiving surface  48   b  over an entire circumference, and an O-ring  64  is fitted therein. As a result, the stem  40  is airtightly slid against the partitioning member  48 , and a sealing function of the upper side of the pressure chambers  46  is secured. In addition, as in the case of the O-ring  62 , the O-ring  64  is fitted into the second fitting part  481  with friction by its own elastic force due to collapse and deformation. 
     Therefore, the O-ring  64  does not fall off even when the stem  40  elevates and lowers. Further, as in the case of the O-ring  62 , the O-ring  64  is exposed to the pressure chambers  46 . Therefore, when the valve  1  is fully opened, the O-ring  64  is pressed against the inner wall of the second fitting part  481  by the pressure of the working fluid acting on the pressure chambers  46 . This pressing force further promotes collapse and deformation of the O-ring  64  in the second fitting part  481 , and further improves the sealing performance of each of the pressure chambers  46 . 
     Further, as in the case of the O-ring  62 , since the O-ring  64  is fitted into the second fitting part  481 , thermal expansion is allowed to some extent. Therefore, advertise effects caused by the thermal expansion of the O-ring  64  in a limited space as in the conventional cases, or deterioration of the O-ring  64  and influence on the sealing performance of a lower side of the pressure chamber  46 , are reduced. 
     Further, the bottom wall  45   f  of the housing  45  has a function similar to that of the partitioning member  48  in a sense of partitioning the lower side of the pressure chambers  46 , and an O-ring  65  is exposed to the pressure chambers  46  and fitted into a third fitting part  4522  provided on the bottom wall  45   f,  and has a function similar to that of the O-ring  64 . Therefore, the sealing function of the lower side of the pressure chambers  46  is secured. 
     The first pressure receiving surface  47   b  is formed with a counterbored part  49  through which the radial holes  41   b  of the flow passage  41  communicates when the first pressure receiving surface  47   b  is brought into contact with the second pressure receiving surface  48   b  or the bottom wall  45   f  as the stem  40  lowers. When a stroke amount of the stem  40  is increased by a stroke adjusting mechanism, the first pressure receiving surface  47   b  may come into contact with the second pressure receiving surface  48   b  or the bottom wall  45   f  as the stem  40  lowers. When the first pressure receiving surface  47   b  is brought into contact with the second pressure receiving surface  48   b  or the bottom wall  45   f,  malfunction of the valve  1  may occur since a required volume of the pressure chambers  46  cannot be secured and the radial holes  41   b  are blocked. In addition, there is a possibility that the O-ring  62  comes into contact with the partitioning member  48  and the O-ring  62  is damaged. 
     However, by forming the counterbored part  49  on the first pressure receiving surface  47   b,  even if the first pressure receiving surface  47   b  comes into contact with the second pressure receiving surface  48   b , the working fluid can be supplied to a space of the counterbored part  49  since the radial holes  41   b  are opened in the space of the counterbored part  49 . Therefore, the space of the counterbored part  49  is secured as the pressure chambers  46 . 
     Further, it is not necessary to secure a large pressure chamber  46  when the valve  1  is fully closed in anticipation of a safety factor in order to avoid contact between the first pressure receiving surface  47   b  and the second pressure receiving surface  48   b  and the bottom wall  45   f,  and it is not necessary to secure an outer shape of the actuator  4  longer in the axial direction. Therefore, the valve  1  can be miniaturized while ensuring a reliability of the actuator  4 , and, consequently, the valve  1 . 
     In addition, the stroke amount of the stem  40  can be adjusted smaller by the stroke adjustment mechanism to improve responsiveness and controllability of the opening and closing operation of the valve  1 . Further, the O-ring  62 , the O-ring  64 , and the O-ring  65  are exposed to the counterbored part  49  when the first pressure receiving surface  47   b  comes into contact with the second pressure receiving surface  48   b  as the stem  40  lowers. 
     As a result, when the valve  1  is shifted from a fully closed state to a fully open state and the working fluid is supplied to the pressure chambers  46 , the O-ring  62 , the O-ring  64  and the O-ring  65  are pressed by the working fluid and are crushed and deformed in the space of the counterbored part  49 . Thus, even if the first pressure receiving surface  47   b  comes into contact with the second pressure receiving surface  48   b,  the sealing function of each pressure chambers  46  is secured by forming the counterbored part  49 . 
     Opening and Closing Operation of Valve 
     Next, an opening and closing operations of the valve  1  will be described. When the working fluid is supplied to the two pressure chambers  46  through the flow passage  41  from the supply port  53   a,  the piston  47  and the stem  40  are pulled up against an elastic force of the spring  42  by the pressures of each pressure chambers  46 . As a result, the diaphragm  30  becomes a natural state having a convex cross section by its own restoring force and is separated from the valve seat  23 , and the valve  1  is opened. 
     On the other hand, the supply of the working fluid from the supply port  53   a  is stopped and the pressures inside of the flow passage  41  and the two pressure chambers  46  are released, the piston  47  and the stem  40  are lowered by the elastic force of the spring  42 . As a result, a central part of the diaphragm  30  is pressed downward by the diaphragm retainer  43 , is deformed into a concave cross section shape against its own restoring force and is separated from the valve seat  23 , and the valve  1  is closed. 
     Sensor Unit  5   
     The sensor unit  5  is a functional unit sensing an operation of the valve  1 , and as illustrated in  FIGS.  2  to  5   , it is provided above the actuator  4 . This sensor unit  5  has an opening and closing operation detecting sensor  50  composed with a magnet  501  and a magnetic sensor  502 , and a sensor cap  53 , and the opening and closing operation detecting sensor  50  is stored in the sensor cap  53 . 
     The sensor cap  53  is attached above the actuator cap  451  and covers the opening and closing operation detecting sensor  50  and the like with a part protruding from the actuator cap  451  of the stem  40 . An upper surface of the sensor cap  53  is provided with the supply port  53   a  of the working fluid, a cable outlet  53   b  leading a cable  56  to an outside, and a through hole  53   c  where an LED cap  53   d  is fitted. 
     An annular fourth fitting part  533  is formed at a part leading to the supply port  53   a  of the working fluid and at a position corresponding to an upper part of the stem  40 . An O-ring  67  is fitted into the fourth fitting part  533 , and as a result, airtightness between the sensor cap  53  and the stem  40  is maintained in a vicinity of the supply port  53   a.    
     A cable holder  561  holding the cable  56  is provided in the cable outlet  53   b,  and the cable  56  is prevented from wobbling or being bent at a part of the cable outlet  53   b  by this cable holder  561 . The LED cap  53   d  has translucency and is a member having a shape that conforms to shape the through hole  53   c.  This LED cap  53   d  transmits a light of an LED stored in the sensor cap  53  to an outside at a state of being fitted into the through hole  53   c.    
     A bolt hole  53   e  for attaching the sensor cap  53  to the actuator cap  451  is formed on a side of the sensor cap  53 . As illustrated in  FIG.  6   ,  FIG.  7 A ,  FIG.  7 B , and  FIG.  7 C , this bolt hole  53   e  is in a shape that conforms to shape the bolt  53   f,  and is provided with an expanding diameter part  531  tapered outward and a hole part  532  conforming to shape a shank part of the bolt  53   f.  On an inner peripheral surface of the hole part  532 , an internal thread corresponding to an external thread formed on an outer peripheral surface of the bolt  53   f  is formed, and is threadedly engaged with the bolt  53   f.    
     Above an outer peripheral surface of the actuator cap  451  where the sensor cap  53  is attached, a lower part of the sensor cap  53  is covered and a concaved fastening groove  45   c  fastening a tip of the bolt  53   f  is formed. When the actuator cap  451  is covered with the sensor cap  53  from top, the bolt hole  53   e  is positioned at a place where the fastening groove  45   c  is formed. In addition, in a vicinity of an opening of the fastening groove  45   c,  an inclined part  4511 , tapered so as to expand diameter toward an outside, is provided. 
     Referring now to  FIG.  7 A ,  FIG.  7 B , and  FIG.  7 C , a process to mount the sensor cap  53  and the actuator cap  451  will be described. First, as illustrated in  FIG.  7 A , the actuator cap  451  is covered with the sensor cap  53 . Then, as illustrated in  FIG.  7 B , the bolt  53   f  is inserted from the bolt hole  53   e  of the sensor cap  53  to the fastening groove  45   c  of the actuator cap  451 , and the external thread of the bolt  53   f  is threadedly engaged with the internal thread of the hole part  532 . At this time, the tip of the shank part of the bolt  53   f  is guided deep into the hole part  532  while contacting with the expanding diameter part  531 . As illustrated in  FIG.  7 C , the bolt  53   f  is threadedly engaged with the bolt hole  53   e  and is fastened deep into the fastening groove  45   c.  At this time, a tip of the shank part of the bolt  53   f  is guided to a groove bottom of the fastening groove  45   c  by the inclined part  4511  formed in the fastening groove  45   c  of the actuator cap  451 . When the tip of the shank part of the bolt  53   f  is pressed against the groove bottom of the fastening groove  45   c,  the sensor cap  53  is fixed to be un-rotatable toward the actuator cap  451 . 
     As a result of fixing the sensor cap  53  to the fastening groove  45   c  provided in the actuator cap  451  with the bolt  53   f,  alignments between the cable outlet  53   b  of the sensor cap  53  and the cable  56 , and between the LED cap  53   d  and the LED  57 , are easy, unlike the case where the sensor cap  53  is threadedly engaged with the actuator cap  451  to be attached while being rotated. In addition, even in a state where the cable  56  is led out from the cable outlet  53   b,  the cable  56  can be fixed without applying a burden. Furthermore, since the sensor cap  53  is attached to the actuator cap  451  by fastening the bolts  53   f  at three places from the side, the sensor cap  53  is not inclined with respect to the actuator cap  451 . Further, the inclined part  4511  formed in the fastening groove  45   c  of the actuator cap  451  serves as a guide, so that fastening positions in an axial direction of the bolts  53   f  at the three places becomes equal to each other, and the sensor cap  53  does not incline. 
     Opening and Closing Operation Detecting Sensor  50   
     In this embodiment, the opening and closing operation detecting sensor  50  is attached on an upper surface of an outer surface of the actuator cap  451 . This opening and closing operation detecting sensor  50  has a detecting means to detect an opening and closing operation of the diaphragm  30  accompanying the elevating and lowering of the stem  40 , or the opening and closing operation of the valve  1 , based on changes in a magnetic field caused by elevating and lowering of the magnet  501  attached to the stem  40 . Further, the pressure in the pressure chamber  46 , the stroke amount of the diaphragm retainer  43 , and a thrust force and an average moving speed of the piston  47 , can be detected or calculated based on the changes in the magnetic field. Information obtained from this opening and closing operation detecting sensor  50  can be used for abnormality determination of the operation of the valve  1 . 
     As illustrated in  FIG.  3    and  FIG.  4   , the magnet  501  is a ring-shaped magnetic body and is attached to a stepped part provided in the stem  40  so that the stem  40  protruding upward from the through hole  45   a  of the actuator cap  451  is inserted therethrough. Since the magnet  501  is in a ring-shaped, a magnetic field generated by the magnet  501  can be reliably and accurately detected regardless of a position of the magnetic sensor  502  provided around the stem  40 . 
     In addition, at a predetermined position of the stem  40 , an O-ring  66  is provided as an elastic member for fixing the magnet  501  to the stem  40 , and this O-ring  66  contacts with the magnet  501  from above and to fix the magnet  501  to the predetermined position of the stem  40 . As illustrated in  FIG.  6   , an annular recess  40   b  is formed on a part which is an outer peripheral surface  40   a  of the stem  40  and is extending from the through hole  45   a  of the actuator cap  451 . This recess  40   b  is formed at regular intervals along a circumferential direction of the stem  40 . In addition, an inclined part  405 , tapered so as to expand diameter from an inside to an outside, is provided at an upper and lower ends of the recess  40   b.    
     As a result, the O-ring  66  is fitted into the recess  40   b,  so that the O-ring  66  holds down the magnet  501  without shifting in the axial direction of the stem  40 , and the magnet  501  is reliably fixed to the predetermined position. In particular, the O-ring  66  contacts with the inclined part  405  in an upper part of the recess  40   b  so as to be pressed downward, so that the magnet  501  is pressed downward from above to be firmly fixed. Further, since an upper surface of the magnet  501  is in contact with the O-ring  66  over an entire circumference and is restrained by generating frictional resistance, a rotation of the magnet  501  in the circumferential direction with respect to the stem  40  is prevented. In addition, by fixing with an elastic member of the O-ring  66 , it is possible to suppress vibration or the like during the opening and closing operation of the valve  1  transmitted from the stem  40  to the magnet  501 . As a result, the magnetic sensor  502  can accurately detect the magnetic field generated by the magnet  501  moving only in a vertical direction. Further, the magnet  501  can be attached or detached by attaching or detaching the O-ring  66 , which is simple. 
     Since the stem  40  is fixed so as to be vertically movable by the O-rings  65  and  67 , the stem  40  vertically moves along the axial direction without tilting. In addition, since the stem  40  is held by a plurality of O-rings, and the stem is not rotated by a spring  42  and the like which is wound around the stem  40 , the magnet  501  is not rotated together with the stem  40 . 
     In addition, in the present embodiment, a diameter of the stem  40  is slightly smaller than that of other parts at a position where the magnet  501  is attached, and a lower end surface of the magnet  501  is supported so as to be in contact with a stepped surface of the stem  40  without any gap. 
     The magnetic sensor  502 , for example, is a contactless sensor using the Hall effect, detects the magnetic field into an electric signal magnetic field generated by the magnet  501 , converts a change in the magnetic field into an electric signal, and outputs the electric signal. An operation type of the magnetic sensor  502  may be any, but for example, a latching type or a switching type may be used. In addition, it may be using a coil, or it may be using an AMR element whose resistance value changes according to a strength and direction of the magnetic field, as long as a position of the magnet  501  can be detected without contact in combination with the magnet  501 . 
     As illustrated in  FIG.  4    and  FIG.  5   , the magnetic sensor  502  is clamped and fixed by a sensor base  51  and a sensor holder  52 . In this embodiment, the sensor base  51  is formed in a rectangular parallelepiped shape, and is provided with an elongated hole  51   a  for fixing to the upper surface of the actuator cap  451  and a bolt hole  51   c  for attaching the sensor holder  52 . 
     The elongated hole  51   a  is an elliptic shape hole having a length in a radial direction of the stem  40  when the sensor base  51  is attached on the actuator cap  451 . As a result, the sensor base  51  can adjust a position to attach within a range where the bolt hole  45   b  of the actuator cap  451  and the elongated hole  51   a  of the sensor base  51  overlap. By adjusting the position to attach the sensor base  51  within the range of a length of the elliptic shape elongated hole  51   a,  the sensor holder  52  can move closer to or conversely away from the magnet  501  attached to the stem  40  to fix, and a distance between the magnet  501  and the magnetic sensor  502  held by the sensor holder  52  can be adjusted. In such a configuration, it can be said that the elongated hole  51   a  constitutes an adjusting means adjusting the distance between the magnetic sensor  502  and the magnet  501 . 
     In this embodiment, the sensor holder  52  is formed of a rectangular plate-like member and has a pair of the bolt holes  52   a  to which the bolts  51   d  are threadedly engaged, and an opening  52   b  is provided between the pair of the bolt holes  52   a.  The sensor holder  52  is attached to a surface on a side of the stem  40  of the sensor base  51 , and is fixed to the sensor base  51  while the magnetic sensor  502  is clamped by the bolts  51   d  which are threadedly engaged with the bolt holes  52   a  through the bolt holes  51   c.    
     When the magnetic sensor  502  is clamped by the sensor holder  52  and the sensor base  51 , the magnetic sensor  502  is exposed from the opening  52   b  to a side of the magnet  501 . As a result, the magnetic sensor  502  can reliably detect the magnetic field generated by the magnet  501 . 
     The magnetic sensor  502  is connected to a circuit board  54 , and wirings  55  are integrated from the circuit board  54  and led out of the valve  1  as the cable  56  through the cable outlet  53   b  of the sensor cap  53 . The circuit board  54  includes a processing module for transmitting information obtained by the magnetic sensor  502  and for executing information processing based on the information. As a result, the information can be transmitted to an external terminal or the like through the cable  56 . 
     In this embodiment, the circuit board  54  is attached to the upper surface of the actuator cap  451  with the sensor base  51 . For example, a flexible printed circuit (FPC) is used for the circuit board  54 , and a gap between the members can be used as a wiring path to the magnetic sensor  502 . In addition, the processing module may be stored in the valve  1  separately from the circuit board  54 , or may be provided as a part of the magnetic sensor  502 . 
     An LED  57  is connected to the circuit board  54 . The LED  57  is a notification means for notifying status information such as a detection result by the magnetic sensor  502 , an analysis result based on the detection result, or a detection error, and emits light in a predetermined color or light emitting pattern according to contents of the notification. The light from the LED  57  is visible from the outside through the LED cap  53   d.    
     According to the valve  1  of the present embodiment, the operation of the valve  1  can be accurately detected. In particular, since the magnet  501  is securely fixed to the stem  40  and the stem  40  exhibits stable behavior without tilting, a detection accuracy of the opening and closing operation is high. Furthermore, the sensor unit  5  is provided above the valve  1 , and replacement and visual recognition are easy. In particular, since the sensor unit  5  is attached to the outside of the actuator cap  451 , maintenance such as replacement of the sensor unit  5  itself or the magnet  501  constituting the sensor unit  5  by a member unit can be performed without touching parts, such as the pressure chamber  46  of the actuator  4  or the spring  42 , that affect driving. 
     In another embodiment of the present invention, as illustrated in  FIG.  8   , the sensor base  51  or the circuit board  54  may be attached to a top surface of the inside of the sensor cap  53 , whereby the opening and closing operation detecting sensor  50  can be attached to the inside of the sensor cap  53 . As a result, the opening and closing operation detecting sensor  50  can be easily replaced by changing the sensor cap  53 . In addition, since a vibration of the actuator  4  is less likely to be transmitted to the opening and closing operation detecting sensor  50 , it is suitable for improving detection accuracy. 
     In the above-described present embodiment, the valve  1  may be provided with an information display means, such as a liquid crystal panel, for displaying operation information. In addition, a means for outputting a notification sound may be provided in accordance with a processing result by a stored software application. 
     As illustrated in  FIG.  9   , a plurality of the valves  1 , described above, may constitute a fluid control device  10  (gas unit) together with a flow rate control device  11  (hereinafter also referred to as a mass flow controller  11 ) and the like. The fluid control device  10  is provided by a plurality of gas lines  10 A (three lines in  FIG.  9   ) adjacent in a width direction and each of the gas lines  10 A is installed on a base metal plate. In each of the gas lines  10 A on the substrate, a plurality of valves  1  and  7 , connected through a block joint  12 , are arranged in a row together with components, such as the mass flow controller  11 . In the present embodiment, the valve  1  is provided on a downstream side of the flow rate control device  11 , but the valve  1  may be provided on a side of the valve  7 . 
     In addition, the counterbored part  49  and the actuator  4  may be provided with a pair of the piston  47  and the pressure chamber  46  for each, or two or more for each. Further, the actuator  4  and the sensor unit  5  are not limited to the air operation valve, and can be applied to a valve having other driving source or a driving object other than the valve. In addition, the actuator cap  451  and the actuator body  452  are fastened by threadedly engaged, but they may be fastened by other fastening methods. Further, the stem  40  is constituted by the rod  402  and the stem body  401 , but it may be integrally formed. Although the present embodiment illustrates a two-way valve in which two flow passages, the fluid inflow passage  20  and the fluid outflow passage  21  are formed in the valve body  2 , a three-way valve having three flow passages may be used. 
     REFERENCE SIGNS LIST 
     
         
           1  valve 
           2  valve body 
           10  fluid control device 
           30  diaphragm (valve disk) 
           31  bonnet 
           32  bonnet nut 
           4  actuator 
           40  stem 
           401  stem body 
           402  rod 
           405  inclined part 
           42  spring 
           451  actuator cap 
           4511  inclined part 
           452  actuator body 
           45   a  through hole 
           45   b  bolt hole 
           45   c  fastening groove 
           46  pressure chamber 
           47  piston 
           48  partitioning member 
           5  sensor unit 
           50  opening/closing operation detecting sensor (detecting means) 
           501  magnet (magnetic body) 
           502  magnetic sensor 
           51  sensor base 
           51   a  elongated hole 
           51   b  bolt 
           51   c  bolt holes 
           51   d  bolt 
           52  sensor holder 
           52   a  bolt hole 
           52   b  opening 
           53  sensor cap 
           53   a  supply port 
           53   b  cable outlet 
           53   c  through hole 
           53   d  LED cap 
           53   e  bolt holes 
           53   f  bolt 
           54  circuit board 
           55  wiring 
           56  cable 
           61 ,  62 ,  63 ,  64 ,  65 ,  66 ,  67  O-ring