Abstract:
Provided are: a flow path switching valve that reduces the pressure load in a contact surface outer peripheral section of the flow path switching valve and inhibits friction between constituent components; and a liquid chromatographic device using the flow path switching valve. The flow path switching valve is provided with a stator having a plurality of through holes and a seal having conduction grooves for causing the through holes to conduct. The seal has a first portion present vertically beneath a region comprising at least a surface of contact with the stator, and a second portion having lower rigidity than the first portion, on the outside of the first portion. Due to this configuration, it is possible to reduce the pressure load when a flow path of a liquid is switched under high-pressure conditions, and inhibit the phenomenon of friction itself.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a fluid switching valve that switches a flow path of liquid. Further, the present invention relates to a liquid chromatograph apparatus and a liquid chromatograph system using the fluid switching valve. 
       BACKGROUND ART 
       [0002]    In most products in an analyzer for liquid, a fluid switching valve that switches a flow path of liquid is used. For example, in a liquid chromatograph apparatus, a fluid switching valve that switches a flow path under high-pressure conditions is used in order to transport a sample as an analysis subject, which is introduced into a mobile phase flow path, to a column for separation of each component. 
         [0003]      FIG. 16  shows a structure of a general fluid switching valve of the related art. Basically, the fluid switching valve includes: a stator  102  having through holes  101  to which fluid inlet-outlet tubes are connected; and a rotor seal  104  that is connected to the stator  102 . The stator  102  and the rotor seal  104  seal a flow path so as to prevent fluid from leaking to the outside while rubbing against each other through a contact surface. 
         [0004]    As a countermeasure against the rubbing between the stator and the rotor seal in the fluid switching valve, PTL 1 describes a method of providing a space on a contact surface side of either the stator or the rotor seal to reduce an area where rubbing occurs. 
       CITATION LIST 
     Patent Literature 
       [0005]    PTL 1: Pamphlet of International Publication No. WO2012/109103 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0006]    Recently, the speed and volume of a feeding pressure of fluid have increased, and thus a fastening load of a valve has also increased. That is, a load applied to the contact surface between the stator and the rotor seal has increased, and thus the contact surface is more likely to be worn away. 
         [0007]    The rotor seal is formed of a material having higher flexibility than a material of the stator in most cases and rotates around the stator. Therefore, in particular, the rotor seal is likely to be worn away. A contact surface outer peripheral portion between the stator and the rotor seal has a long moving distance during rotation, and thus wear debris is likely to be produced. As a result, the contact surface may be further scratched, or the produced wear debris may be incorporated into a flow path. 
         [0008]    However, in the technique described in PTL 1, the space is provided in the contact surface to physically reduce the area of the contact surface which may be worn away. However, since the other area of the contact surface is still likely to be worn away, the above-described problem may still occur. 
         [0009]    In addition, in PTL 1, the space provided in the contact surface between the stator and the rotor seal requires high processing accuracy during molding such that burrs and the like produced during the formation of the space do not scratch the contact surface during the rotation of the rotor seal. Further, there is limitation in the arrangement of the space. For example, it is necessary that the space is formed at a predetermined distance from a flow path of the stator and the rotor seal. 
         [0010]    An object of the present invention is to provide: a fluid switching valve that reduces a rubbing phenomenon occurring between the stator and the rotor seal; and a liquid chromatograph apparatus using the fluid switching valve. 
       Solution to Problem 
       [0011]    As a result of thorough investigation, the present inventors found a configuration which contributes to a reduction in pressure applied to a contact surface between a stator and a rotor seal, the pressure being one of the reasons for the rubbing phenomenon in a fluid switching valve. That is, according to an aspect of the present invention for solving the above-described problems, there are provided a fluid switching valve and a liquid chromatograph apparatus using the fluid switching valve, the fluid switching valve including: a stator having a plurality of through holes; and a seal having a connection groove through which the through holes are connected to each other, in which the seal includes at least a first portion that is present vertically downward with respect to a region containing at least a contact surface with the stator, and a second portion that is provided outside the first portion and has lower rigidity than the first portion. 
       Advantageous Effects of Invention 
       [0012]    According to the aspect, a fluid switching valve and an apparatus using the fluid switching valve can be provided, in which a rubbing phenomenon can be reduced by reducing a pressure applied to a contact surface outer peripheral portion instead of reducing the area of a contact surface between a stator and a rotor seal. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0013]      FIG. 1 -A is a diagram showing an overall configuration example of a fluid switching valve according to an embodiment of the present invention. 
           [0014]      FIG. 1 -B is a diagram showing a configuration example (first example) of a fluid switching valve according to an embodiment (Embodiment 1) of the present invention. 
           [0015]      FIG. 2  is a diagram showing the reason why a recess according to the embodiment of the present invention reduces a pressure applied to a contact surface outer peripheral portion. 
           [0016]      FIG. 3  is a diagram showing a top surface of a rotor seal according to the embodiment of the present invention. 
           [0017]      FIG. 4  is a diagram showing a pressure change on a contact surface which varies depending on whether or not the recess according to the embodiment of the present invention is present. 
           [0018]      FIG. 5  is a diagram showing a positional relationship between an inner diameter of the recess according to the embodiment of the present invention, and a flow path and the contact surface. 
           [0019]      FIG. 6  is a diagram showing a configuration example (second example) of the fluid switching valve according to the embodiment (Embodiment 1) of the present invention. 
           [0020]      FIG. 7 -A is a diagram showing a configuration example (third example) of a fluid switching valve according to an embodiment (Embodiment 2) of the present invention. 
           [0021]      FIG. 7 -B is a diagram showing a configuration example (fourth example) of the fluid switching valve according to the embodiment (Embodiment 2) of the present invention. 
           [0022]      FIG. 8  is a diagram showing a configuration example (fifth example) of the fluid switching valve according to the embodiment (Embodiment 2) of the present invention. 
           [0023]      FIG. 9  is a diagram showing a configuration example (sixth example) of the fluid switching valve according to the embodiment (Embodiment 2) of the present invention. 
           [0024]      FIG. 10  is a diagram showing a configuration example (seventh example) of the fluid switching valve according to the embodiment (Embodiment 2) of the present invention. 
           [0025]      FIG. 11  is a diagram showing a configuration example (eighth example) of the fluid switching valve according to the embodiment (Embodiment 2) of the present invention. 
           [0026]      FIG. 12  is a diagram showing a configuration example (ninth example) of the fluid switching valve according to the embodiment (Embodiment 2) of the present invention. 
           [0027]      FIG. 13  is a diagram showing a configuration example (tenth example) of a fluid switching valve according to an embodiment (Embodiment 3) of the present invention. 
           [0028]      FIG. 14  is a diagram showing a configuration example (eleventh example) of the fluid switching valve according to the embodiment (Embodiment 3) of the present invention. 
           [0029]      FIG. 15  is a diagram showing a configuration of a liquid chromatograph using the fluid switching valve according to an embodiment (Embodiment 4) of the present invention. 
           [0030]      FIG. 16  is a diagram showing a configuration of a fluid switching valve of the related art. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0031]    Hereinafter, embodiments of the present invention will be described using the drawings. 
       Embodiment 1 
       [0032]    In this embodiment, an example of a fluid switching valve that reduces a pressure applied to a contact surface outer peripheral portion between a stator and a seal will be described. 
         [0033]      FIG. 1  is a diagram showing a configuration example of the fluid switching valve according to the embodiment of the present invention.  FIG. 1 -A is an overall configuration diagram of the valve, and  FIG. 1 -B is a diagram showing a configuration example (first example) of the valve, which is an enlarged cross-sectional view showing contact between a stator and a rotor seal. 
         [0034]    The fluid switching valve  100  includes a stator  102 , a rotor seal  104 , a bearing  108 , a rotor  109 , a housing  110 , a plate spring  111 , a plate spring bearing  112 , a bearing  113 , a washer  114 , a housing  115 , and a nut  116 . The stator  102  includes through holes  101 . The rotor seal  104  includes a connection groove  103 , a pin through hole  106 , and a recess  107  that is formed on a surface of the rotor seal  104  opposite to a contact surface with the stator  102 . The rotor seal  104  is arranged so as to be in contact with the stator  102  and is rotatable due to the rotor  109 . The stator  102 , the housing  110 , and the housing  115  are fixed through a screw. 
         [0035]    The configuration of the fluid switching valve according to the embodiment is different from the configuration of the fluid switching valve of the related art shown in  FIG. 16 , in that the recess  107  is provided on the surface of the rotor seal  104  opposite to the contact surface with the stator  102 . With the above-described configuration, the pressure applied to the outer peripheral portion of the contact surface  105  can be reduced as described below. 
         [0036]    Next, a mechanism will be described using  FIG. 2  in which the recess  107  shown in  FIG. 1  exhibits an effect of reducing the pressure applied to the outer peripheral portion of the contact surface  105  between the stator  102  and the rotor seal  104 . 
         [0037]      FIG. 2  is a diagram showing the reason why the recess according to the embodiment reduces the pressure applied to the contact surface outer peripheral portion. 
         [0038]    The stator  102  and the rotor seal  104  receive a fastening load in the vertical direction in order to prevent liquid leakage from a flow path including the through holes  101  and the connection groove  103 . Focusing on a relationship between the stator  102  and the rotor seal  104 , this load is balanced on the contact surface  105 . Therefore, when the top surface of the rotor seal  104  has the same shape (area) as that of the contact surface  105  as shown in  FIG. 2(A) , a load  201  on the stator  102  side and a load  202  on the rotor seal  104  side are well-balanced in the contact surface  105 . However, as shown in  FIG. 2  (B), according to the shape of the existing rotor seal  104 , the entire area of the top surface is wider than that of the contact surface  105 . Therefore, a load  203  is newly added to the load  201  applied from the stator  102  side such that the load  201  is supported in a contact surface outer peripheral portion  117  which is a region of the top surface of the rotor seal  104  positioned outside of the contact surface  105 . As a result, the contact surface outer peripheral portion  117  is likely to be worn away because a higher load is applied thereto than the center of the contact surface  105 . 
         [0039]    Therefore, as shown in  FIG. 2  (C), the rotor seal  104  has a structure in which the recess  107  is provided on the surface of the rotor seal  104  opposite to the contact surface and in which a region that is present vertically downward with respect to a region containing at least the contact surface has higher rigidity than the other peripheral region. With the above-described structure, a seal member in the peripheral region can be reduced, the seal member is likely to be deformed, and the magnitude of the load  203  can be reduced as compared to  FIG. 2(B) . 
         [0040]    Next, the effect of the recess  107  shown in  FIG. 2  reducing the pressure applied to the contact surface outer peripheral portion  117  was verified using a finite element method, and the result thereof will be described.  FIG. 3  is a diagram showing a top surface of the rotor seal  104 .  FIG. 4  is a diagram showing a pressure change on the contact surface which varies depending on whether or not the recess  107  according to the embodiment of the present invention is present.  FIG. 4  is a graph showing a value obtained by subtracting a pressure value of a structure where the recess  107  is not provided from a pressure value of a structure where the recess  107  is provided, the pressure being a surface pressure in an X direction in  FIG. 3 , that is, in an arrow direction moving from a center point O of the rotor seal  104  shown in  FIG. 3  to the center of each of the through holes  101  positioned so as not to overlap the connection groove  103 . The stator  102  is formed of stainless used steel (SUS), and the rotor seal  104  is formed of a resin material which is polyether-ether-ketone (PEEK). The horizontal axis represents a distance x from the center point O of the rotor seal  104  in the X direction in  FIG. 3 . The vertical axis represents a difference value in the pressure on the contact surface at the distance x. A range of x from about 1.1 mm to 1.4 mm corresponds to the through holes  101 . Therefore, irrespective of whether or not the recess  107  is present, a force is not applied to the contact surface, and the surface pressure is zero. A range of x from about 1.75 mm to 2.2 mm corresponds to the outer peripheral portion of the contact surface between the stator  102  and the rotor seal  104 . In this portion, in the structure where the recess  107  is provided, the surface pressure of the contact surface outer peripheral portion  117  is lower as compared to the structure where the recess  107  is not provided. That is, the rubbing phenomenon which occurs during the rotation of the seal can be reduced. Further, a range of x of about 1.1 mm or a range of x from 1.4 mm to 1.7 mm from the center point O, that is, the peripheral region of the through holes  101  which is a flow path exhibits a higher surface pressure in the structure where the recess  107  is provided than the structure where the recess  107  is not provided. This leads to improvement of sealing characteristics of the flow path. In addition, focusing on a surface pressure distribution, in the structure where the recess  107  is not provided, the surface pressure gradually increases toward the outer peripheral portion of the contact surface. However, in the structure where the recess  107  is provided, the surface pressure distribution is uniform as a whole. That is, according to the above-described configuration, the fastening load can be efficiently distributed in a plane. Accordingly, even when the fastening load is lower than that in the related art, sufficiently high sealing characteristics can be obtained. A reduction in the fastening load leads to a reduction in the power of a motor required to rotate the rotor seal  104 , and it can also be expected that a structure of the motor will be simplified. When the surface pressure is uniform, it can be expected that a variation in the amount of wear in a radial direction will be reduced. Due to these effects, the product lifetime of the valve can be extended. 
         [0041]    Conditions of the configuration of the recess  107  which are effective to reduce the pressure applied to the contact surface outer peripheral portion  117  will be described using  FIG. 5 .  FIG. 5  is a diagram showing a positional relationship between an inner diameter of the recess according to the embodiment of the present invention and a flow path and the contact surface. An outer diameter of the connection groove  103  is represented by a, an inner diameter of the recess is represented by b, and a diameter of an outermost periphery  303  of the contact surface  105  is represented by c. At this time, it is preferable that a≦b is satisfied because a sufficient pressure is necessary on the outside of the connection groove  103 , which is the flow path, in order to prevent liquid leakage. In addition, it is preferable that b≦c is satisfied because the seal positioned outside the outermost periphery of the contact surface generates the load  203 . That is, when the inner diameter b of the recess  107  is set so as to satisfy a≦b≦c, the surface pressure applied to the outer peripheral portion of the contact surface  105  can be efficiently reduced. 
         [0042]    The stator  102  and the rotor seal  104  can be freely selected according to the specification of the valve. The above-described pressure reduction effect does not depend on a combination between a material of the stator  102  and a material of the rotor seal  104 . During the formation of the recess  107 , in the case of a resin material such as PEEK, injection molding or cutting after molding is performed. In the case of a metal material such as SUS, cutting is performed.  FIG. 6  is a diagram showing a configuration example (second example) of the fluid switching valve according to the embodiment (Embodiment 1) of the present invention. During the above-described cutting, a tool is used. Therefore, as in the recess  107  shown in the drawing, a nose radius  601 , which is curved according to the tool, may be provided on a corner portion. In this way, during the processing, a position where the recess  107  is provided is not the contact surface containing the flow path. Therefore, high surface accuracy is not necessary, and the processing costs can be suppressed. 
       Embodiment 2 
       [0043]    In this embodiment, various configurations of the recess of the fluid switching valve, which is effective to reduce the surface pressure applied to the contact surface outer peripheral portion  117 , will be described. 
         [0044]      FIG. 7 -A is a diagram showing a configuration example (third example) of the fluid switching valve according to the embodiment (Embodiment 2) of the present invention. 
         [0045]    The description of portions having the same functions as the above-described components represented by the same reference numerals in the fluid switching valve  100  of  FIG. 1  will not be repeated. In a case where the inner diameter of the recess  107  is set so as to satisfy the conditions described in Embodiment 1, the recess  107  may be formed on a side surface of the rotor seal  104  as shown in  FIG. 7 -A. Even in this case, the region that is present vertically downward with respect to the region containing at least the contact surface has higher rigidity than the other peripheral region. Therefore, the same surface pressure reduction effect as in Embodiment 1 can be obtained. In addition, with this method, the recess does not exist on the surface of the rotor seal  104  contacting the rotor  109 . Therefore, the area of the contact surface between the rotor seal  104  and the rotor  109  increases, and contact stability is improved. 
         [0046]      FIG. 7 -B shows a configuration example (fourth example) in which the rotor seal  104  of  FIG. 7 -A is vertically divided into two portions and a shim member  118  is inserted between the two portions. According to the configuration shown in  FIG. 7 -B, each of the divided portions of the rotor seal is easily processible, and the costs can be reduced as compared to the configuration shown in  FIG. 7 -A. Further, the shim member  118  which is inserted between the two portions of the rotor seal member reduces inclination of the contact surface between the stator  102  and the rotor seal  104 . As a result, a compressive force is uniformly distributed on the contact surface between the stator  102  and the rotor seal  104 , and the sealability of the flow path can be maintained. 
         [0047]    It is preferable that the shim member  118  is formed of a resin material such as PEEK having high compressive strength. 
         [0048]      FIG. 8  shows a configuration example (fifth example) of the fluid switching valve according to the embodiment (Embodiment 2) of the present invention. As shown in  FIG. 8 , a T-shaped structure may be adopted in which the portion of the rotor seal  104  that is present vertically downward with respect to the region containing at least the contact surface with the stator  102  remains by removing an outer peripheral region of the portion. When the rotor seal  104  formed of metal is used during cutting and the like, the method of removing the outer peripheral portion as shown in  FIG. 8  is simpler than the method of adopting the groove shape as shown in  FIG. 1  or  7 . According to this configuration, a wide contact surface between the stator  102  and the rotor seal  104  can be secured, and thus it is easy to perform a surface treatment on the contact surface. 
         [0049]      FIG. 9  shows a configuration example (sixth example) of the fluid switching valve according to the embodiment (Embodiment 2) of the present invention. As shown in  FIG. 9 , an inverted T-shaped structure may be adopted in which the portion of the rotor seal  104  that is present vertically downward with respect to the region containing at least the contact surface with the stator  102  remains and a space is provided by removing an outer peripheral region of the portion. According to this configuration, a wide bottom surface of the rotor seal  104  can be secured, and thus stability is improved. 
         [0050]      FIG. 10  shows a configuration example (seventh example) of the fluid switching valve according to the embodiment (Embodiment 2) of the present invention. As shown in  FIG. 10 , a step may be provided to the recess. According to this configuration, it is easy to perform a surface treatment on the contact surface between the stator  102  and the rotor seal  104 , and contact stability can be improved. 
         [0051]      FIG. 11  shows a configuration example (eighth example) of the fluid switching valve according to the embodiment (Embodiment 2) of the present invention. As shown in  FIG. 11 , a projection portion may be provided around the pin through hole  106 . The rotor seal  104  is connected to the rotating rotor  109  through a pin which passes through the pin through hole  106 . Therefore, reinforcement using the projection portion may be performed depending on the usage environment of the valve. 
         [0052]      FIG. 12  shows a configuration example (ninth example) of the fluid switching valve according to the embodiment (Embodiment 2) of the present invention. As shown in  FIG. 12 , a gap  1201  maybe provided in the rotor seal  104 . For example, a seal including the gap  1201  as shown in  FIG. 12  can be manufactured by using additive manufacturing such as 3D printing. 
       Embodiment 3 
       [0053]    In this embodiment, a configuration of a fluid switching valve in which regions having different rigidities are provided instead of the space of the recess  107  formed in the above-described examples will be described. 
         [0054]      FIG. 13  shows a configuration example (tenth example) of the fluid switching valve according to the embodiment (Embodiment 3) of the present invention.  FIG. 13  shows an example of a configuration diagram of the fluid switching valve  100  according to Embodiment 3. In a region where rigidity is desired to be improved, a high-density region  1301  having a higher density than a material constituting the rotor seal  104  is provided. For example, in the case of a seal formed of a resin, the above-described configuration can be realized by filling the portion of the high-density region  1301  with the resin with a higher pressure than in the other regions. 
         [0055]      FIG. 14  shows a configuration example (eleventh example) of the fluid switching valve according to the embodiment (Embodiment 3) of the present invention. As shown in  FIG. 14 , a different material-embedded region  1401  may be provided by embedding an internal space of the rotor seal  104  with a different material from a material of the rotor seal  104 . For example, the rigidity of the different material-embedded region  1401  can be improved to be higher than the other region by using a resin as the material of the rotor seal  104  and using SUS as the material of the different material-embedded region  1401 . As an embedding method of the different material, various methods can be used, and examples thereof include a method of forming a recess in the rotor seal  104  in advance and embedding this recess with a different material. In addition, the different material-embedded region  1401  can be manufactured by preparing a material such as SUS as a different Material in advance and casting a resin material onto the vicinity of the different material. 
       Embodiment 4 
       [0056]    In this embodiment, a configuration of a liquid chromatograph apparatus using the fluid switching valve  100  will be described. 
         [0057]      FIG. 15  is a block diagram showing the liquid chromatograph apparatus according to the embodiment of the present invention. 
         [0058]    A mobile phase  1501  is fed to a separation column  1504  by a pump  1502 . The separation column  1504  is arranged in a thermostatic chamber  1505 . An auto sampler  1503  including the fluid switching valve  100  introduces a sample into a flow path of the mobile phase fed by the pump  1502 . The fluid switching valve  100  causes the sample which is a separation object to flow into the separation column  1504  together with the mobile phase  1501 . The sample and the mobile phase  1501  flowing into the separation column  1504  moves to a outflow side while repeating absorption/desorption for each component in the separation column  1504 . As a result, each chemical component constituting the sample is separated. 
         [0059]    Each component separated by the separation column  1504  is detected by a detector  1506 . 
         [0060]    According to the embodiment, the pressure applied to the contact surface outer peripheral portion  117  is reduced due to a difference in rigidity between the lower portion of the contact surface of the fluid switching valve  100  and the peripheral region around the lower portion. Therefore, the probability that the sample is erroneously detected by wear debris incorporating into the flow path is reduced. In addition, the occurrence of a rubbing phenomenon is reduced, and thus the replacement cycle of the valve can be extended. In this way, a fluid switching valve having superior detection performance and durability and a liquid chromatograph apparatus using the valve can be obtained. 
         [0061]    The present invention is not limited to the above-described embodiments and includes various modification examples. For example, the above-described embodiments have been described in detail for easy understanding of the present invention and does not necessarily include all the configurations described above. In addition, a part of a configuration of an embodiment may be replaced with a configuration of another embodiment. Further, a configuration of an embodiment maybe added to a configuration of another embodiment. In addition, regarding a part of the configuration of each of the embodiments, addition of another configuration, deletion, or replacement can be made. 
       REFERENCE SIGNS LIST 
       [0000]    
       
           100 : FLUID SWITCHING VALVE 
           101 : THROUGH HOLE 
           102 : STATOR 
           103 : CONNECTION GROOVE 
           104 : SEAL 
           105 : CONTACT SURFACE 
           106 : PIN THROUGH HOLE 
           107 : RECESS 
           108 : BEARING 
           109 : ROTOR 
           110 : HOUSING 
           111 : PLATE SPRING 
           112 : PLATE SPRING BEARING 
           113 : BEARING 
           114 : WASHER 
           115 : HOUSING 
           116 : NUT 
           117 : CONTACT SURFACE OUTER PERIPHERAL PORTION 
           118 : SHIM MEMBER 
           201 : LOAD APPLIED TO CONTACT SURFACE FROM STATOR SIDE 
           202 : LOAD APPLIED TO CONTACT SURFACE FROM SEAL SIDE 
           203 : LOAD APPLIED TO CONTACT SURFACE OUTER PERIPHERAL PORTION 
           301 : OUTER PERIPHERAL CONTACT PORTION OF THROUGH HOLE  101   
           302 : OUTER PERIPHERY OF RECESS 
           303 : OUTERMOST PERIPHERY OF CONTACT SURFACE  105   
           304 : INNER PERIPHERY OF RECESS 
           601 : NOSE RADIUS 
           1201 : GAP 
           1301 : HIGH-DENSITY REGION 
           1401 : DIFFERENT MATERIAL-EMBEDDED REGION 
           1501 : MOBILE PHASE 
           1502 : PUMP 
           1503 : AUTO SAMPLER 
           1504 : SEPARATION COLUMN 
           1505 : THERMOSTATIC CHAMBER 
           1506 : DETECTOR