Multiport valve for water quality analyzer

Abstract

This prevents fluid leakage from within the multi-port valve caused by stress being applied to the stator from multiple directions. [Solution] The multi-port valve 1 for a water quality analyzer has a valve head 4 on its outer surface which has multiple ports 6 for connecting piping, and has a connection surface where the ends of flow paths 8 leading to each of the ports 6 are arranged in the same plane, and is made of a resin material that is corrosion-resistant to the chemicals used in the water quality analyzer; a rotor 14 which has a flat surface on which grooves 16 are formed for switching the connection state between the ends of the flow paths 8 arranged on the connection surface, and which is arranged so that the flat surface faces the connection surface; and a drive mechanism 22 for rotating the rotor 14.

Description

[Technical Field]

[0001] The present invention relates to a multiport valve for a water quality analyzer. [Background technology]

[0002] In water quality analyzers, syringe pumps are used to perform processes such as sample collection, reagent aspirate, reagent addition to the sample, sample delivery to the oxidation reaction section, and sample delivery to the measurement section. These processes are performed by switching the flow path connected to the syringe pump using a multiport valve (see Patent Document 1).

[0003] Water quality analyzers often use highly corrosive reagents such as strong acids and strong alkalis. Therefore, all parts of the water quality analyzer that may come into contact with the reagents must be made of materials that are corrosion-resistant to the reagents. For this reason, the multi-port valves used in water quality analyzers are designed to prevent reagents from coming into contact with metal parts.

[0004] Specifically, a multiport valve is composed of a valve body, a valve head, a rotor, and a stator. The valve head is a metal component attached to the tip of the valve body. The valve head has multiple female threaded holes for fixing pipes. The stator is attached to the valve head and has internal flow paths that communicate with the pipes fixed to the female threaded holes in the valve head. The rotor has grooves that connect the flow paths in the stator, and rotates while sliding against the stator to switch the flow paths in the stator that are connected. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-015387 Summary of the Invention [Problem to be solved by the invention]

[0006] In the multiport valve of a water quality analyzer, to prevent highly corrosive reagents and the like from coming into contact with the metal valve head, the pipes are fastened to the female threaded holes in the valve head with the ends of the pipes pressed against the stator with great force, sealing the connection between the flow path and the pipes inside the stator. Because of this structure, stress is applied from multiple directions to the stator against which the ends of the multiple pipes are pressed, and if this stress is particularly uneven, it can deform the stator or the ferrules attached to the ends of the pipes, resulting in liquid leakage inside the multiport valve.

[0007] If a liquid leak occurs inside a multiport valve, corrosion or rust can occur in the metal valve head, leading to problems such as poor water collection, crystallization of reagents, and sticking of fittings. This can also cause the stator to stick to the valve head, which in the worst case scenario could make it impossible to replace the stator.

[0008] SUMMARY OF THE INVENTION It is therefore an object of the present invention to prevent fluid leakage from within a multiport valve caused by stress being applied to a stator from multiple directions. [Means for solving the problem]

[0009] The multi-port valve for a water quality analyzer of the present invention has a valve head that has a plurality of ports on its outer surface for connecting piping, and has a connection surface in which the ends of the flow paths leading to each of the ports are arranged in the same plane, and is made of a resin material that is corrosion-resistant to the chemicals used in the water quality analyzer; a rotor that has a flat surface on which grooves are formed for switching the connection state between the ends of the flow paths arranged on the connection surface, and is arranged so that the flat surface faces the connection surface; and a drive mechanism for rotating the rotor.

[0010] That is, the multiport valve for a water quality analyzer of the present invention is not structured so that the ends of the pipes are pressed against a stator, but rather has a valve head made of a corrosion-resistant material, and the pipes are connected to flow paths provided within the valve head. In short, the multiport valve for a water quality analyzer of the present invention does not have a structure in which the ends of the pipes are pressed against a stator from multiple directions.

[0011] In the present invention, a stator fixed to the valve head side may be interposed between the flat surface of the rotor on which the grooves are formed and the connection surface of the valve head.

[0012] In the above case, if the rotor and the stator are made of the same material, their sliding surfaces may be polished and stick together, causing the rotor and the stator to become stuck. Therefore, the rotor and the stator can be made of materials with different hardnesses. This can prevent the rotor and the stator from sticking together. Furthermore, if one of the rotor and the stator is made of a material softer than the other, the one made of the softer material will elastically deform, improving the sealing between the two.

[0013] In the present invention, a stator does not have to be interposed between the valve head and the rotor, i.e., the flat surface of the rotor on which the groove is formed may be in direct contact with the connecting surface of the valve head.

[0014] In the above case, the rotor can be made of a resin material that is softer than the valve head, which makes the rotor more susceptible to wear than the valve head due to sliding between the valve head and rotor, thereby suppressing wear on the valve head.

[0015] The valve head can be made of a fluororesin, such as polytetrafluoroethylene (PTFE) or polychlorotrifluoroethylene (PCTFE).

[0016] A stator fixed to the valve head can be interposed between the flat surface of the rotor on which the groove is formed and the connecting surface of the valve head. In this case, at least one of the rotor and the stator can be made of a resin material. This improves the sealing performance between the rotor and the stator because the resin material is easily elastically deformed.

[0017] In the above case, the rotor may be made of a fluororesin.

[0018] The stator may be made of a fluororesin material. [Effects of the Invention]

[0019] The multi-port valve for a water quality analyzer according to the present invention has a valve head made of a corrosion-resistant material, and piping is connected to a flow path provided within the valve head. Therefore, it does not have a structure that presses the ends of the piping against the stator from multiple directions, and liquid leakage caused by such a structure does not occur. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a cross-sectional view showing an embodiment of a multi-port valve for a water quality analyzer. FIG. [Figure 2] FIG. 10 is a cross-sectional view showing another embodiment of the multi-port valve for a water quality analyzer. [Figure 3] This is an image showing the condition of the flow path after a PPS valve head has been used for a long period of time. [Figure 4] This is an image showing the condition of the flow path when a PCTFE valve head is used for a long period of time. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, an embodiment of a multiport valve for a water quality analyzer will be described with reference to the drawings.

[0022] In one embodiment, a multiport valve 1 for a water quality analyzer comprises a valve body 2 and a valve head 4. The valve head 4 is attached to the tip of the valve body 2. A plurality of ports 6 consisting of female threaded holes for connecting piping are provided on the outer surface of the valve head 4. The ports 6 communicate with flow paths 8 provided inside the valve head 4, and the ends of the flow paths 8 are located on a flat surface 4a of the valve head 4, which forms the innermost surface of the internal space of the valve body 2. The flat surface 4a of the valve head 4 forms a connection surface where the ends of the flow paths 8 communicating with each port 6 are arranged on the same plane.

[0023] A stator 10 is attached to the flat surface 4a of the valve head 4. The stator 10 is interposed between the valve head 4 and a rotor 14 (described later) and slides against the rotor 14. The stator 10 has a through hole 12 at a position corresponding to the end of the flow path 8 provided on the flat surface 4a.

[0024] Inside the valve body 2, the rotor 14 is held at the tip 18a of the rotor shaft 18. The rotor 14 has a flat surface that faces the flat surface 4a of the valve head 4, and this flat surface is provided with grooves 16 for connecting the ends of each flow path 8. The flat surface of the rotor 14 with the grooves 16 abuts against the stator 12, and as the rotor shaft 18 rotates, the rotor 14 rotates while sliding against the stator 12, switching the ends of the flow paths 8 that are connected.

[0025] The rotor shaft 18 is biased toward the valve head 4 by an elastic member such as a coil spring, which constantly presses the rotor 14 against the stator 10. The rotor shaft 18 is rotated by a stepping motor 22. The rotor shaft 18 and stepping motor 22 form a drive mechanism for rotating the rotor 14.

[0026] In the multiport valve 1 for a water quality analyzer of this embodiment, at least the valve head 4, stator 10, and rotor 14 are made of a material that is corrosion-resistant to reagents that may be used in the water quality analyzer. Examples of such materials include PPS (polyphenylene sulfide), PEEK (polyether ether ketone), PTFE (polytetrafluoroethylene), PCTFE (polychlorotrifluoroethylene), and ceramics.

[0027] In particular, the use of a fluororesin such as PTFE or PCTFE as a corrosion-resistant material can prevent rust and blockage of flow paths due to dissolution or erosion of the material. The inventors examined the durability of valve heads 4 when PPS and PCTFE were used as the material for the valve head 4. When the valve head 4 made of PPS was used for a long period of time, blockage of the flow paths formed in the valve head 4 occurred, as shown in FIG. 3. In contrast, when the valve head 4 made of PCTFE was used for a long period of time, blockage of the flow paths formed in the valve head 4 did not occur, as shown in FIG. 4. This suggests that using a fluororesin such as PCTFE as the material for the valve head 4, as well as the stator 10 and rotor 10, can effectively prevent blockage of flow paths due to dissolution or erosion of the material.

[0028] In particular, by constructing the valve head 4 from the above-mentioned corrosion-resistant material, highly corrosion-resistant chemicals such as strong acids and strong alkalis can flow through the flow path 8 inside the valve head 4. Therefore, there is no need to press the piping through which these chemicals flow against a member other than the valve head 4 (for example, a stator) to seal it.

[0029] With this structure, the sealing surfaces inside the valve 1 are limited to the surfaces between the valve head 4 and the stator 10, and the surfaces between the stator 10 and the rotor 14, and stress is applied only in a direction perpendicular to the sealing surfaces. In other words, the fastening force of the fitting for connecting the piping acts only on the valve head 4, and stress is not applied in any direction other than the direction perpendicular to the sealing surfaces inside the valve 1.

[0030] It is preferable that the stator 10 and the rotor 14 are made of materials with different hardness (for example, ceramic and PEEK). In this case, the member made of the soft material will elastically deform, improving the sealing performance between the stator 10 and the rotor 14. In particular, since the rotor 14 is a replaceable consumable item, it is more preferable that the rotor 14 be made of a material (for example, PEEK) softer than the stator 10.

[0031] As in the multiport valve 1' for a water quality analyzer shown in Figure 2, the rotor 14 may be in direct contact with the valve head 4 without a stator between them. In this case, it is preferable to make the rotor 14 out of a material softer than the valve head 4 in order to suppress wear on the valve head 4. For example, the valve head 4 may be made of PPS, and the rotor 14 may be made of PEEK.

[0032] With the structure shown in Figure 2, the only sealing surface inside the valve 1' is the surface between the valve head 4 and the rotor 14, and the fastening force of the fitting for connecting the piping acts only on the valve head 4, so stress is applied only in the direction perpendicular to the sealing surface inside the valve 1'. [Explanation of symbols]

[0033] 1.1" Multiport valve for water quality analyzer 2 Valve body 4 valve head 6 ports 8 Flow path 10 Stator 12 Through holes 14 rotors 16 groove 18 Rotor shaft 20 Elastic member 22 Stepping motor

Claims

1. A valve head forming the outer surface of a multi-port valve, having a plurality of ports on said outer surface for connecting piping, and having a connection surface in which the ends of flow paths leading to each of said ports are arranged in the same plane, said flow paths being liquid-contacting parts that come into contact with a corrosive reagent for water quality analysis, while being made of polychlorotrifluoroethylene, thereby preventing blockage of said flow paths due to said corrosive reagent; a rotor having a flat surface on which grooves for switching a connection state between ends of the flow paths arranged on the connection surface are formed, the flat surface being arranged to face the connection surface; a drive mechanism for rotating the rotor, a stator fixed to the valve head side is interposed between a flat surface of the rotor on which the groove is formed and the connection surface of the valve head, The multiport valve for a water quality analyzer, wherein the stator is made of ceramic, and the rotor is made of a resin that is softer than ceramic.

2. 2. The multiport valve for a water quality analyzer according to claim 1, wherein the rotor is made of a fluororesin.

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