Comparing Electrodes and Electrochemical Measurement Devices

Abstract

The present invention provides a comparative electrode and an electrochemical measurement device that can suppress potential fluctuations for a long period of time with a simple structure without increasing the size. The comparative electrode comprises: a cylindrical housing having a liquid junction provided at the distal end and a sealed proximal end; an internal liquid filled within the housing; a tube housed within the housing, the tube being sealed on the liquid junction side and having an opening formed on the side opposite the liquid junction; and an internal electrode disposed within the tube on the liquid junction side and positioned closer to the liquid junction than the opening. The tube is configured to extend from the distal end of the housing toward the proximal end and is disposed away from the inner end surface of the proximal end of the housing.

Description

[0001] This application is a divisional application of patent application No. 201310099527.X, filed on March 26, 2013, and entitled “Comparison Electrode and Electrochemical Measuring Device”. Technical Field

[0002] The present invention relates to a comparative electrode (reference electrode) used in electrochemical measuring devices such as ion electrode devices and ORP electrode devices, and particularly to a sealed comparative electrode suitable for use in which internal liquid does not need to be replenished until discarded. Background Art

[0003] When using ion electrode methods such as pH electrodes, a comparison electrode (also called a reference electrode, standard electrode, etc.) is required. In recent years, there has been a growing demand in the market for so-called sealed comparison electrodes that do not require internal liquid replenishment until disposal.

[0004] Because these sealed internal electrodes come into contact with the liquid being measured (hereinafter referred to as the sample liquid), diluting the internal liquid, they can cause potential fluctuations if used continuously for extended periods of time. Consequently, as described in Patent Document 1 and other publications, measures such as gelling the internal liquid or installing filters to inhibit ion permeation have been employed.

[0005] The mechanism by which the potential fluctuation occurs is as follows.

[0006] (1) Supporting electrolyte ions such as chloride ions contained in the internal liquid diffuse into the contacting sample liquid.

[0007] (2) The diffusion of chloride ions starts from the liquid junction and spreads to the entire internal liquid.

[0008] (3) The chloride ion concentration around the internal electrode decreases, causing potential fluctuations.

[0009] According to the mechanism described above, the concentration reduction caused by the diffusion of chloride ions does not cause a potential change until it reaches the vicinity of the internal electrode. Therefore, assuming that the diffusion rate is constant, the time until the potential change occurs can be extended by increasing the distance from the liquid junction to the internal electrode, thereby extending the time that can be used continuously.

[0010] Prior art literature

[0011] Patent Document 1: Japanese Re-Publication No. 2008-32790

[0012] However, due to market demands and design constraints, simply increasing the sensor's external dimensions to extend the distance from the liquid junction to the internal electrode is unrealistic and not an ideal solution. Summary of the Invention

[0013] The present invention focuses on the processes (1) and (2) above, and its main purpose is to provide a comparison electrode that can suppress potential fluctuations for a long time with a simple structure without causing the external dimensions of the comparison electrode to become larger.

[0014] That is, the present invention provides a comparative electrode, comprising: a shell, which is cylindrical and has a liquid junction provided on the front end side and is sealed on the base end side; an internal liquid filled in the shell; a tube accommodated in the shell, the liquid junction side of the tube being sealed, and the tube having an opening formed on the side opposite to the liquid junction; and an internal electrode, which is provided in the tube on the liquid junction side and is arranged closer to the liquid junction than the opening, the tube being arranged to extend from the front end side to the base end side of the shell, and the tube being arranged to be away from the inner end surface of the base end side of the shell.

[0015] In addition, the present invention provides a comparison electrode, which includes: a shell filled with an internal liquid; an internal electrode immersed in the internal liquid in the shell; a liquid junction portion, which is configured so that one end is exposed to the inside of the shell and in contact with the internal liquid, and the other end is exposed to the outside of the shell; and a partition wall arranged in the shell, the partition wall maintains the continuity of the internal liquid in the shell from the liquid junction portion to the internal electrode, and divides the imaginary straight line connecting the internal electrode and the liquid junction portion.

[0016] With this comparative electrode, the shortest path from the liquid junction through the internal liquid to the internal electrode is longer than a straight line connecting the liquid junction and the internal electrode. Therefore, compared to a case without a partition, it takes longer for the sample liquid to reach the vicinity of the internal electrode and reduce the concentration of the internal liquid around the internal electrode. As a result, compared to conventional technologies, the time until potential fluctuations occur is longer, allowing for long-term measurement accuracy. This effect is particularly pronounced during continuous use.

[0017] Furthermore, for example, by simply providing a partition wall within the casing of an existing comparative electrode, the above-mentioned effect can be achieved with a very simple structure without causing an increase in size or cost.

[0018] As a specific embodiment of maintaining the continuity of the internal liquid from the liquid junction to the internal electrode, an opening connecting the spaces is provided on the partition wall that divides the shell into a liquid junction side space belonging to the liquid junction and an internal electrode side space belonging to the internal electrode.

[0019] As a specific embodiment that can more reliably exhibit the above effect, for example, the opening is provided at a position farther away from the liquid junction than a portion of the internal electrode closest to the liquid junction.

[0020] In other words, the path from the opening to the internal electrode side space of the internal electrode only needs to pass through a position farther from the liquid junction than the tip portion of the internal electrode closest to the liquid junction.

[0021] In order to effectively utilize the limited space in the housing, it is preferred that the electrode passes through a path farther from the liquid junction than the front end portion, then passes through a position closer to the liquid junction than the front end portion, and then reaches the internal electrode.

[0022] In order to enable simple manufacturing using a tube, etc., and to suppress as much as possible the concentration change of the internal liquid around the internal electrode caused by mixing even if vibration is generated by external force, thereby more reliably suppressing the potential change, it is preferred that the partition wall is formed as a cylinder, the opening is provided at the front end of the cylinder, the internal electrode is arranged on the base end side of the cylinder, and the opening of the cylinder is facing the side opposite to the liquid junction.

[0023] In a method in which the liquid junction is provided at the front end portion of the shell and the internal electrode is arranged on the base end side of the shell, in order to extend the path from the opening to the internal electrode as much as possible, it is preferred that the cylinder extends from the base end side to the front end side of the shell, and is bent from the extended end of the cylinder and further extends toward the base end side of the shell, and the opening is formed at the extended front end of the cylinder.

[0024] In a method in which the liquid junction is provided at the front end portion of the shell and the internal electrode is arranged near the liquid junction, in order to extend the path from the opening to the internal electrode as much as possible, it is preferred that the cylinder extends from the front end side to the base end side of the shell, and the opening is provided at the front end of the extension of the cylinder.

[0025] Alternatively, a structure may be adopted in which the partition wall is not provided and the outer wall of the housing divides the imaginary straight line connecting the internal electrode and the liquid junction. This structure can also achieve the same function and effect.

[0026] Specifically, in a structure in which the liquid junction is provided at the front end portion of the housing and the internal electrode is arranged at the base end portion of the housing, the housing may be in a curved tubular shape.

[0027] As a specific embodiment in which the effects of the present invention are particularly remarkable, a sealed comparative electrode in which the internal liquid is not replenished from the start of use until disposal can be cited.

[0028] The present invention also provides an electrochemical measuring device comprising: a comparison electrode according to the present invention; a measuring electrode; a computing unit configured to output measurement data representing a measurement result based on output values ​​from the comparison electrode and the measuring electrode; and a main unit communicatively connected to the computing unit for displaying the measurement result in a predetermined format based on the measurement data output from the computing unit. This electrochemical measuring device extends the time until the potential fluctuation occurs compared to conventional devices, enabling continuous electrochemical measurement while maintaining measurement accuracy over a long period of time.

[0029] In addition, if the present invention, which can suppress the occurrence of potential fluctuations for a long time, is expressed from another perspective, it is a comparison electrode, which includes: a shell filled with an internal liquid; an internal electrode immersed in the internal liquid in the shell; and a liquid junction portion, which is configured such that one end is exposed to the inside of the shell and contacts the internal liquid, and the other end is exposed to the outside of the shell, and the outer wall of the shell divides an imaginary straight line connecting the internal electrode and the liquid junction portion.

[0030] The present invention also provides an electrochemical measuring device comprising: the aforementioned comparison electrode; a measuring electrode; a computing unit configured to output measurement data representing a measurement result based on the output values ​​from the comparison electrode and the measuring electrode; and a main unit communicatively connected to the computing unit for displaying the measurement result in a predetermined format based on the measurement data output from the computing unit. This electrochemical measuring device maintains measurement accuracy over a long period of time without potential fluctuations.

[0031] In addition, in a liquid analyzer provided with a plurality of sensors such as comparison electrodes and measuring electrodes of the present invention, in order to make the orientation of each sensor surface consistent without strictly managing the precision of the orientation of each sensor surface even in a structure in which multiple sensors are provided with sensor surfaces inclined relative to the extension axis, and in order to easily clean each sensor surface, for example, the following liquid analyzer is sufficient: the liquid analyzer analyzes the liquid to be measured while immersed in the liquid to be measured, and comprises: a plurality of sensors, the front end of which becomes a sensor surface immersed in the liquid to be measured, the sensor surface being inclined relative to the extension axis; a main body, formed with a plurality of insertion holes, the base end side of each sensor being inserted into the plurality of insertion holes along the extension axis; and an insertion angle limiting structure, which limits the insertion angle of the sensor when the sensor is inserted into the insertion hole so that each sensor surface faces a specified direction.

[0032] According to the liquid analyzer, the sensors are simply inserted into the insertion holes of the main body respectively. Since no threads are formed between the sensors and the insertion holes, the insertion angles of the sensors relative to the insertion holes can be freely changed even when the sensors are in the middle of being inserted into the insertion holes or after the sensors are inserted into the insertion holes respectively.

[0033] Furthermore, the liquid analyzer of the present invention employs a structure in which the sensors have a degree of freedom related to the insertion angle relative to the insertion hole. Therefore, the insertion angle limiting structure restricts the insertion angle of the sensors, thereby allowing the sensor surfaces to face a predetermined direction. Therefore, since the sensor surface of each sensor can be set in a predetermined direction, the orientation of each sensor surface can be unified in a predetermined direction.

[0034] Even in a liquid analyzer equipped with multiple sensors whose sensor surfaces are tilted relative to the extension axis, each sensor surface can be aligned in a predetermined direction. This ensures that the liquid being measured strikes each sensor surface in a substantially uniform manner, even when there is flow in the liquid being measured. Consequently, even when there is flow in the liquid being measured, variations in the measured values ​​and sensitivity of each sensor can be suppressed, enabling high-precision analysis.

[0035] Furthermore, since the sensor surfaces can be made uniform, when designing a cleaning mechanism for cleaning the sensor surfaces, for example, the flow of the cleaning liquid can be limited to substantially the same direction, and a simple structure can be employed.

[0036] In addition, as shown in the present invention, each sensor is inserted into each insertion hole respectively, and the insertion angle of each sensor is limited by the insertion angle limiting structure so that each sensor surface faces a specified direction. As long as this structure is adopted, compared with the case where the sensor surfaces are made consistent by strictly performing precision management of the threads, there is no need to increase the parts required for precision management, thereby suppressing the increase in manufacturing costs.

[0037] Here, the phrase "aligning the sensor surfaces in a predetermined direction using the insertion angle limiting structure" means, for example, that the flow rate of the liquid in contact with each sensor surface is aligned to the point where there is virtually no difference, even when there is a flow of the liquid being measured. In other words, this means aligning the orientation of the sensor surfaces to the point where variations in measured values ​​and sensitivity fall within an acceptable range. Alternatively, this could mean aligning the sensor surfaces to the point where, for example, a liquid flow from one direction generated by a cleaning mechanism can sufficiently remove dirt from the sensor surfaces.

[0038] To maintain each sensor in a fixed position relative to the main body while the sensors face a predetermined direction, and to reduce the number of steps and complexity compared to attaching each sensor individually to the main body, a pressing mechanism is provided to collectively press the multiple sensors against the main body. This structure eliminates the need to screw each sensor into the main body individually; instead, the pressing mechanism secures all sensors together. This eliminates the problem of difficulty in screwing each sensor into the main body due to interference with other sensors caused by fingers or tools when screwing the sensors into the main body.

[0039] In order to make the sensor surfaces naturally face the specified direction as soon as the sensors are inserted into the mounting holes, thereby making the installation operation of the sensors very simple, the following scheme can be adopted: the insertion angle limiting structure is composed of the shape of the insertion hole and the shape of the sensor, and each shape is formed in the following manner: only when the sensor is inserted into the insertion hole at an insertion angle that makes the sensor surface face the specified direction, the sensor is roughly fitted into the insertion hole, so that the base end of the sensor can be inserted to the specified depth of the mounting hole.

[0040] As a simple structure for orienting the sensor surfaces in a predetermined direction, at least a portion of the insertion hole and at least a portion of the sensor cross section may be formed into substantially the same D-shape.

[0041] Another specific example of a structure for aligning the sensor surfaces in a predetermined direction and ensuring alignment of the sensor surfaces is that the sensor includes a pin extending radially relative to the extension axis, and the insertion hole includes a fitting groove for engaging the pin. Furthermore, by varying the position and shape of the pin in each sensor and providing a corresponding fitting groove in each insertion hole, the sensor surfaces can be aligned in a predetermined direction and the combination of each sensor with each insertion hole can be prevented from being mismatched.

[0042] As a specific structure for uniformly pressing and securing the sensors against the main body with sufficient force, the following configuration can be cited: The pressing mechanism includes: an engaging member having multiple through-holes extending through the distal end of each sensor, the engaging member engaging with an engaging portion formed on each sensor; a connecting member disposed so as to surround the space outside the sensors and connect between the engaging member and the main body; and a threaded portion formed between the connecting member and the main body. The engaging member is mounted so as to be rotatable relative to the connecting member about the central axis of the threaded portion. By screwing the connecting member onto the main body using the threaded portion, the distance between the engaging member and the main body is reduced. According to this configuration, since the connecting member is disposed so as to surround the space outside the sensors, the diameter of the threaded portion can be increased compared to a case where the threads are directly provided on the sensors. Therefore, even when manually rotating the connecting member, a large torque can be easily generated, allowing the engaging member to press the sensors against the main body with sufficient force.

[0043] To prevent a decrease in measurement accuracy and sensitivity, etc., which may result from dirt and the like adhering to each sensor surface due to the sensor surface being continuously immersed in the liquid being measured, a liquid analysis system comprising the liquid analyzer and a cleaning mechanism that generates a liquid flow or vibration in the liquid being measured to clean each sensor surface facing a predetermined direction may be sufficient. According to this liquid analysis system, since each sensor surface in the liquid analyzer faces a predetermined direction, even with a simple liquid flow or vibration wave generated in the liquid being measured by the cleaning mechanism, each sensor surface can be sufficiently cleaned without complicating the cleaning mechanism.

[0044] According to the present invention having the above-described structure, the shortest route from the liquid junction through the internal liquid to the internal electrode is longer than the route connecting the liquid junction and the internal electrode with a straight line. Therefore, compared with the case where there is no partition wall, it takes longer for the sample liquid to reach the vicinity of the internal electrode and cause the concentration of the internal liquid around the internal electrode to decrease.

[0045] As a result, compared with conventional technologies, the time until potential fluctuation occurs is prolonged, and measurement accuracy can be maintained for a long time.

[0046] Furthermore, according to the liquid analyzer of the present invention, even if each sensor has a sensor face that is tilted relative to the extension axis, the insertion angle limiting structure can align each sensor face with a predetermined direction. Therefore, even when a liquid flow exists within the measurement target liquid, the sensor faces can be aligned with the direction of the liquid flow, maintaining a constant contact state with the measurement target liquid in each sensor. This can suppress variations in the measured values ​​and sensitivity of each sensor, thereby improving analysis accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 FIG. 1 is an overall schematic diagram of an electrochemical measuring device according to one embodiment of the present invention.

[0048] Figure 2 is with Figure 1 is a schematic diagram of a measuring electrode of the same embodiment.

[0049] Figure 3 is with Figure 1 Schematic diagram of a comparative electrode of the same embodiment.

[0050] Figure 4 It is a schematic diagram of a comparative electrode according to another embodiment of the present invention.

[0051] Figure 5 is a schematic diagram of a comparative electrode according to another embodiment of the present invention.

[0052] Figure 6 is a schematic diagram of a comparative electrode according to another embodiment of the present invention.

[0053] Figure 7 is a schematic diagram of a measuring electrode according to another embodiment of the present invention.

[0054] Figure 8 is a schematic diagram of a measuring electrode according to another embodiment of the present invention.

[0055] Figure 9 is a schematic diagram of a measuring electrode according to another embodiment of the present invention.

[0056] Figure 10 It is an overall perspective schematic diagram of an ammonia meter according to another embodiment of the present invention.

[0057] Figure 11 is with Figure 10 It is an exploded perspective schematic diagram of the ammonia meter of the same embodiment.

[0058] Figure 12 Is a detailed representation of Figure 10 Schematic diagram of the pressing mechanism of the same embodiment.

[0059] Figure 13This is an overall diagram of a liquid analysis system including a liquid analysis instrument and a cleaning mechanism according to another embodiment of the present invention.

[0060] Figure 14 It is an enlarged view of a cleaning mechanism according to another embodiment of the present invention.

[0061] Description of Reference Numerals

[0062] 100…Electrochemical measuring device

[0063] 2…Comparison electrode

[0064] 21…housing

[0065] 22…Internal electrode

[0066] 23…Liquid junction

[0067] 24...tube (cylinder)

[0068] 24a…Opening

[0069] Q…Internal liquid

[0070] L…imaginary straight line

[0071] 200A…Liquid Analysis System

[0072] 100A…Ammonia meter

[0073] 1A…Main body

[0074] 2A...Press mechanism

[0075] 21A…Engineer

[0076] 22A…Connecting parts

[0077] 23A…Threaded part

[0078] SN1…Ammonium ion electrode

[0079] SN2…Potassium electrode

[0080] SN3…Comparison electrode

[0081] SP1, SP2…Sensor surface DETAILED DESCRIPTION

[0082] Refer to the following Figures 1 to 3 One embodiment of the present invention will be described.

[0083] Figure 1 An electrochemical measuring device 100 according to this embodiment is shown.

[0084] The electrochemical measuring device 100 is, for example, a device for continuously monitoring the ammonium ion concentration or the nitrate ion concentration in the measurement target liquid S (hereinafter also referred to as the sample liquid) charged into the aeration tank 9. Figure 1 As shown, the electrochemical measuring device 100 includes: a probe mechanism A, which is composed of a measuring electrode 1, a comparison electrode 2, a potentiometer 3 and an operator 4; and a main body mechanism B, which is connected to the probe mechanism A in a communicable manner.

[0085] The measuring electrode 1 is an ion electrode for measuring ammonium ions or nitrate ions. Figure 2 As shown, the measuring electrode 1 includes: a cylindrical main body shell 11 filled with an internal liquid P containing potassium chloride as a supporting electrolyte; an internal electrode (silver / silver chloride electrode plate) 12 inserted into the base end side of the main body shell 11 and immersed in the internal liquid P; and a liquid junction 13 formed by attaching an ion-sensitive membrane to an opening provided at the front end of the main body shell 11.

[0086] like Figure 3 As shown, the comparative electrode 2 comprises a cylindrical housing 21, which is filled with an internal liquid Q containing potassium chloride as a supporting electrolyte without any gaps; an internal electrode (silver / silver chloride electrode plate) 22, inserted into the base end of the housing 21 and immersed in the internal liquid Q; and a liquid junction 23, disposed at the front end of the housing 21, with one end exposed to the interior of the housing 21 and in contact with the internal liquid Q, and the other end exposed to the exterior of the housing 21. The comparative electrode 2 is a so-called sealed comparative electrode, in which the internal liquid Q is not replenished from the time of use until disposal.

[0087] The input terminals of the potentiometer 3 are connected to the measuring electrode 1 and the comparison electrode 2 to measure the potential difference therebetween.

[0088] The computing unit 4 calculates the ammonium ion concentration or the nitrate ion concentration based on the output value of the potentiometer 3 and outputs measurement data indicating the calculated concentration value.

[0089] like Figure 1 As shown, main body B includes a general-purpose information processing device, such as a computer or portable terminal (mobile phone or tablet), which includes a CPU, memory, a communication interface, and a display. By installing a specified application, the information processing device can perform the following operations: communicate with probe mechanism A to cause it to perform measurement or calibration operations; calculate measurement results based on the measurement data sent from probe mechanism A; display them in various formats; receive information from other probe mechanisms A via the internet and perform statistical operations; and incorporate GPS location and time information into the measurement data.

[0090] However, in the embodiment, a tube (cylindrical) shaped partition wall (hereinafter referred to as the tube) 24 is provided in the shell 21 of the comparison electrode 2 so as to maintain the continuity of the internal liquid Q filled in the shell 21, while dividing the imaginary straight line L connecting any part of the liquid contacting portion 23 and any part of the internal electrode 22 that contacts the liquid.

[0091] The tube 24 is, for example, U-shaped or J-shaped, and is made of a durable, chemically non-reactive material such as resin, glass, or ceramic. The tube 24 is disposed within the housing 21 and extends from the proximal end of the housing 21 toward the distal end. The tube 24 bends approximately 180 degrees from the extended end, with the distal end 24a directed toward the proximal end of the housing 21. Furthermore, only the distal end of the tube 24 is open within the internal liquid Q, and the internal electrode 22 is inserted into the proximal end of the tube 24. The internal electrode 22 is immersed in the internal liquid Q that enters the tube 24 through the distal end opening.

[0092] In the above-described structure, if the comparative electrode 2 is used for a long period of time, the chloride ions in the internal liquid Q diffuse from the liquid junction 23 into the sample liquid, and the internal liquid Q is gradually diluted from the distal end of the housing 21. In other words, the concentration of the internal liquid Q varies, with the concentration being higher at the proximal end than at the distal end of the housing 21.

[0093] However, in the present comparative electrode 2, the front end opening 24a of the tube 24 is located on the base end side of the shell 21 where the internal liquid Q is not easily diluted, and the internal electrode 22 is actually present at a position away from the front end opening 24a along the length of the tube 24. Therefore, compared with the case where there is no tube 24, it takes more time for the sample liquid to reach the vicinity of the internal electrode 22 and cause the concentration of the internal liquid Q around the internal electrode 22 to decrease.

[0094] As a result, the time until potential fluctuation occurs can be extended compared to conventional techniques, thereby maintaining measurement accuracy over a long period of time. This effect is particularly significant for a sealed reference electrode 2 whose internal liquid Q does not need to be replaced, extending the continuous measurement time and increasing its lifespan.

[0095] Furthermore, for example, since the tube 24 is merely provided in the housing 21 of the existing comparison electrode 2, a very simple structure can be used for implementation, and thus there is little risk of causing an increase in the size of the comparison electrode 2 or an increase in cost.

[0096] Furthermore, in this embodiment, even if vibration or the like is caused by external forces, since the housing 21 is filled with the internal liquid Q without any gaps, mixing of the internal liquid Q due to external forces such as vibration is prevented. Therefore, changes in the concentration of the internal liquid Q around the internal electrode 22 due to such mixing are minimized, and potential fluctuations can be more reliably suppressed. Furthermore, even if mixing of the internal liquid Q occurs within the housing 21 due to external forces, the effects are unlikely to reach the interior of the tube 24.

[0097] In addition, the present invention is not limited to the above-described embodiments.

[0098] For example, Figure 4 As shown, if the length of the tube 24 (the length from the front end opening 24a to the internal electrode 22) is made longer by bending and winding the tube 24 multiple times inside the housing 21, the above effect is further enhanced.

[0099] In addition, in the Figure 4 The outer peripheral wall of the tube 24 as a partition wall divides the space inside the shell into a liquid junction side space S1 and an internal electrode side space S2. The liquid junction 23 belongs to the liquid junction side space S1, and the internal electrode 22 belongs to the internal electrode side space S2. Figure 3 Differently, when an imaginary boundary line C is drawn through the front end of the internal electrode 22, which is the part closest to the liquid junction 23, and the space inside the housing is assumed to be divided into the liquid junction side and the internal electrode side, the opening 24a connecting the spaces S1 and S2 is set to be located in the housing space on the internal electrode side. Figure 4 In the embodiment, the opening 24a is located farther from the liquid junction 23 than the front end portion of the internal electrode 22 on the liquid junction side, thereby increasing the above effect.

[0100] In addition, if Figure 5 As shown, the following structure can also be adopted: the path from the opening 24a to the internal electrode side space S2 of the internal electrode 22 passes through at least the space inside the shell on the internal electrode side divided by the imaginary boundary line C, then passes through the space inside the shell on the liquid junction side, and then reaches the internal electrode 22.

[0101] like Figure 6 As shown, when the internal electrode 22 is arranged near the liquid junction 23, it is sufficient to arrange the tube 24 so as to extend from the front end side to the base end side of the shell, and to provide the opening 24a at the front end of the extended tube 24. Preferably, the opening 24a is provided as close to the base end as possible in the space inside the shell. In addition, it is also possible to make the bottom surface of the base end of the tube contact the liquid junction 23. This is because doing so can make the length of the tube 24 as long as possible, thereby delaying the dilution of the internal liquid around the internal electrode 22. In addition, as Figure 7As shown, the tube 24 may also be bent midway.

[0102] In addition, the partition wall 24 is not limited to being a tube, as Figure 8 As shown, the shape may also be staggered and extend inward from the outer side wall of the housing 21. The partition wall 24 can be provided so that the shortest route from the liquid junction 23 through the internal liquid Q to the internal electrode 22 is longer than the route connecting the liquid junction 23 and the internal electrode 22 by a straight line.

[0103] Furthermore, if Figure 9 As shown, the following structure may also be adopted: the housing 21 itself is bent once or multiple times so that the outer wall 21 a of the housing 21 divides the imaginary straight line L connecting the internal electrode 22 and the liquid junction 23 .

[0104] Alternatively, the internal liquid can be made into a gel-like state, or a filter can be installed to inhibit ion permeation. If the internal liquid is made into a gel-like state, the effects of external agitation can be eliminated, eliminating the need for complete filling of the liquid, thus facilitating assembly. Furthermore, the installation of a filter can extend the time until potential fluctuations occur.

[0105] An operator may also be provided in the main body.

[0106] This comparative electrode is also suitable for use with other ion electrodes, including pH electrodes, and ORP electrodes, and can also be used in electrochemical measurement devices that use other comparative electrodes. The present invention is particularly useful in situations where potential fluctuations during continuous use hinder measurement.

[0107] Refer to the following Figures 10 to 12 A liquid analyzer according to another embodiment of the present invention will be described. Note that the reference numerals assigned to the components of this embodiment are independently assigned to the reference numerals assigned to the components of the aforementioned embodiment.

[0108] The liquid analyzer of this embodiment is, for example, an ammonia meter 100A, which uses the wastewater being treated as the measurement target liquid LQ in an aeration tank where ammonia nitrogen (ammonia nitrogen) is treated by microorganisms in a wastewater treatment process to grasp the ammonium ion concentration contained in the wastewater.

[0109] More specifically, the ammonia meter 100A is a device formed by integrating three sensors SN1, SN2, and SN3. The sensors SN1, SN2, and SN3 include a comparison electrode SN3 for measuring a reference potential; an ammonium ion electrode SN1 for measuring a potential formed by ammonium ions; and a potassium ion electrode SN2 for measuring a potential formed by potassium ions and correcting the interference of potassium ions on ammonium ions.

[0110] like Figure 10 As shown in the perspective view of FIG, the ammonia meter 100A comprises a generally thin cylindrical housing. A carrying chain is attached to the base end of the ammonia meter 100A. The sensor surfaces SP1, SP2, and SP3 of the three sensors SN1, SN2, and SN3 are exposed outward at the distal end. In this embodiment, the sensor surfaces SP1, SP2, and SP3 refer to the surfaces on which the response membranes S11 and S21 of the respective electrodes and the liquid junction S31 are formed, respectively.

[0111] Refer to the following Figures 11 to 12 The details of the insertion angle limiting structure and the pressing mechanism 2A, and the mounting of the sensors SN1, SN2, and SN3 on the main body 1A will be described.

[0112] First, the insertion angle limiting structure is described in detail. Figure 11 As shown, the shapes of the insertion holes PH1, PH2 corresponding to the shapes of the supporting tubes S12, S22 of the sensors SN1, SN2 inclined with respect to the sensor surfaces SP1, SP2 are formed such that only when the sensors SN1, SN2 are inserted into the insertion holes PH1, PH2 at an insertion angle when the sensor surfaces SP1, SP2 are facing the prescribed direction, the sensors SN1, SN2 can be roughly fitted into the insertion holes PH1, PH2, and the base ends of the sensors SN1, SN2 can be inserted into the prescribed depth of the mounting hole, that is, can be inserted into the deepest point where the electrode terminal D is located.

[0113] More specifically, if Figure 11 As shown, the cross-sectional shapes 314 and 324 of the distal ends of the insertion holes PH1 and PH2 are generally D-shaped, and the outer peripheral surfaces of the proximal ends of the thick cylindrical portions S14 and S24 of the sensors SN1 and SN2 also have the same D-shape as the corresponding insertion holes PH1 and PH2. In other words, in this embodiment, the insertion angle limiting structure is formed by the cross-sectional shapes 314 and 324 of the distal ends of the insertion holes PH1 and PH2 and the outer peripheral surfaces of the proximal ends of the thick cylindrical portions S14 and S24 of the sensors SN1 and SN2.

[0114] The inclined sensor surfaces SP1 and SP2 are Figure 11 As long as the sensors SN1 and SN2 are not facing right in the stereoscopic view, they cannot be fully inserted into the insertion holes PH1 and PH2.

[0115] In other words, for sensors SN1 and SN2 having two inclined sensor surfaces SP1 and SP2, simply by fully inserting them, the angle limiting structures 31a and 32a can be used to always insert the sensors SN1 and SN2 at the same insertion angle, and the orientation of the sensor surfaces SP1 and SP2 will always naturally face the specified direction.

[0116] Furthermore, to prevent incorrect insertion of the sensors SN1 and SN2 into the insertion holes PH1 and PH2, resulting in incorrect combinations, a mis-insertion prevention structure is provided. More specifically, as the mis-insertion prevention structure, pins 311 and 321 are provided on the flat surface of the outer circumference of the base end side of the thick cylindrical portions S14 and S24, extending in a direction perpendicular to the flat surface and radially relative to the extension axis. Furthermore, corresponding to the positions of the pins 311 and 321, fitting grooves 312 and 322 are provided in the insertion holes PH1 and PH2, respectively, to fit with the pins 311 and 321.

[0117] Next, the fixing of the pressing mechanism 2A and the sensors SN1 , SN2 , and SN3 to the main body 1A will be described.

[0118] like Figure 11 and Figure 12 As shown, the pressing mechanism 2A includes: a locking component 21A, which is generally in the shape of a circular plate and has through holes TH1, TH2, TH3, and TH4 respectively passing through the front end sides of the sensors SN1, SN2, and SN3 and the thermometer protection tube PA, and the locking component 21A is engaged with the locking portions S16, S26, and S26 formed on the sensors SN1, SN2, and SN3; a connecting component 22A, which is a thin-walled cylinder with open end faces, and is arranged in a manner to surround a space further outward than the sensors SN1, SN2, and SN3, and is connected between the locking component 21A and the main body 1A; and a threaded portion 23A, formed between the connecting component 22A and the main body 1A.

[0119] More specifically, if Figure 12As shown in (a), the threaded portion 23A is composed of a male threaded portion formed on the outer circumference of the front end side of the main body 1A and a female threaded portion formed on the inner circumference of the base end side of the connecting member 22A. With the thermometer protection tube PA and the sensors SN1, SN2, and SN3 inserted into the through-holes TH1, TH2, TH3, and TH4 of the engaging member 21A, if the connecting member 22A is rotated axially, the connecting member 22A becomes threadedly connected to the main body 1A and moves forward toward the main body 1A. Therefore, the engaging member 21A can be used to press the sensors SN1, SN2, and SN3 together toward the main body 1A via the engaging portions S16, S26, and S36. Furthermore, since the connecting member 22A is formed outside the area where the sensors SN1, SN2, and SN3 are concentrated, the diameter of the connecting member 22A can be increased, and the diameter of the threaded portion 23A can also be increased. Therefore, since torque is easily generated, the sensors SN1, SN2, and SN3 can be pressed against the main body 1A with sufficient force.

[0120] Refer to the following Figure 13 and Figure 14 A liquid analysis system 200A as another embodiment of the present invention is described. The liquid analysis system 200A includes: an ammonia meter 100A as a liquid analyzer; and a cleaning mechanism 101A that forms a liquid flow or vibration in the measurement object liquid LQ, thereby cleaning each sensor surface SP1, SP2, and SP3.

[0121] like Figure 13 The overall picture, from Figure 13 The enlarged view of the front end portion of the ammonia meter 100A and the cleaning mechanism 101A as seen from the direction of line D in FIG. Figure 14 As shown, the front end portion of the ammonia meter 100A and the front end of the cleaning mechanism 101A of the liquid analyzing system 200A are immersed in the measurement target liquid LQ in the aeration tank AE.

[0122] More specifically, the ammonia meter 100A is attached to the front end of a rod-shaped detector bracket H, which is arranged to extend from a support bracket ST fixed at a point outside the aeration tank AE through the lid of the aeration tank AE. Furthermore, a monitor M and a data logger DL are mounted on the support bracket ST. The monitor M displays the values ​​measured by the ammonia meter 100A, while the data logger DL records the measured values. The ammonia meter 100A continuously measures the ammonia concentration in the target liquid LQ. In some cases, the aeration tank AE is uncovered and open. Furthermore, the data logger DL may be omitted if it is not necessary to continuously store the values ​​measured by the ammonia meter 100A and it is sufficient to reference the current measured values ​​using the monitor M.

[0123] The cleaning mechanism 101A is described in detail. Figure 14 As shown, the cleaning mechanism 101A is composed of an ultrasonic cleaning machine UC and a jet cleaning machine JW. The ultrasonic cleaning machine UC mainly cleans the sensor surfaces SP1 and SP2 of the ammonium ion electrode SN1 and the potassium ion electrode SN2 that are inclined relative to the extension axis, and the jet cleaning machine JW mainly cleans the sensor surface SP3 of the comparison electrode SN3 that is perpendicular to the extension axis.

[0124] The ultrasonic cleaning machine UC generates ultrasonic vibrations that travel vertically upward in the liquid LQ to be measured. By constantly generating ultrasonic vibrations in the liquid LQ to be measured, the formation of biofilm on the ammonia meter 100A is suppressed. The ultrasonic vibrating unit UC1 is provided so as to face the semicircular side of the front end surface of the ammonia meter 100A where the ammonium ion electrode SN1 and the potassium ion electrode SN2 are provided. More specifically, as Figure 14 As shown, the central axis of the ultrasonic vibrating portion UC1 is radially offset outward relative to the sensor surfaces SP1 and SP2. In other words, the positional relationship between the inclined sensor surfaces SP1 and SP2 and the ultrasonic vibrating portion UC1 is determined so that the vibration plane of the vibration wave generated by the ultrasonic vibrating portion UC1 directly strikes the inclined sensor surfaces SP1 and SP2.

[0125] The jet washer JW forms a liquid flow in the liquid LQ to be measured that flows horizontally relative to the front end surface of the ammonia meter 100A. More specifically, the jet ejection portion JW1 of the jet washer JW is positioned a predetermined distance radially from the outer peripheral surface of the ammonia meter, and forms a liquid flow that flows horizontally below the sensor surface SP3 of the comparison electrode SN3.

[0126] like Figure 14 As shown, the jet ejected from the jet ejection portion JW1 is a fluid stream flowing in a generally uniform direction along the diameter of the front end face of the ammonia meter 100A, intermittently spraying the front end face of the ammonia meter 100A at predetermined intervals. This jet displaces the water in the pipes of each sensor SN1, SN2, and SN3, thereby removing deposits and large scale contaminants from each sensor SN1, SN2, and SN3. Furthermore, since the jet cleaner JW is arranged in the aforementioned manner and the sensor surfaces SP1 and SP2, which are tilted relative to the extension axis, are aligned in a predetermined direction, there is virtually no difference in flow rate between the sensors SN1 and SN2. Consequently, the flow rate has little effect on the measured values ​​of the sensors SN1 and SN2 and the output of the ammonia meter 100A.

[0127] By aligning the sensor surfaces SP1 and SP2 of the ammonium ion electrode SN1 and the potassium ion electrode SN2, the sensor surfaces SP1 and SP2 are aligned in the same direction. This eliminates the need to align the vibrations generated by the ultrasonic cleaning unit UC in random directions for each sensor SP1 and SP2. Instead, the sensor surfaces SP1 and SP2 can be kept clean using only a single ultrasonic vibrating unit UC1. In other words, by aligning the sensor surfaces SP1 and SP2, the ultrasonic cleaning unit UC, while maintaining a simple structure, can uniformly clean the sensor surfaces SP1 and SP2, maintaining consistent measurement accuracy and sensitivity.

[0128] More specifically, by positioning the ultrasonic vibrator UC1 at the indicated position and aligning the orientations of the sensor surfaces SP1 and SP2 of the ammonia meter 100A, which are tilted relative to the axial direction, in a predetermined direction, the ultrasonic waves strike the sensor surfaces SP1 and SP2 in a consistent manner. Consequently, the ultrasonic cleaning device UC can uniformly suppress the formation of biofilm on the sensor surfaces SP1 and SP2.

[0129] Furthermore, the ultrasonic vibrations generated by the continuously operating ultrasonic cleaning machine UC prevent the formation of biofilm on the front end surface of the ammonia meter 100A, and the jets generated by the intermittently operating jet cleaning machine JW blow away attachments and larger dirt on the front end surface of the ammonia meter 100A. Therefore, even in an environment such as that within the aeration tank AE, the sensor surfaces SP1, SP2, and SP3 can be kept clean, making the measurement values ​​of the ammonia meter 100A reliable.

[0130] According to this embodiment, instead of providing one cleaning machine for each sensor SN1, SN2, and SN3, the cleaning mechanism 101A can be made to have sufficient cleaning capability by using only two cleaning machines.

[0131] The cleaning mechanism 101A is not limited to that shown in the above embodiment. For example, the jet cleaner JW may be primarily used to clean the sensor surfaces SP1 and SP2 of the ammonium ion electrode SN1 and the potassium ion electrode SN2, while the ultrasonic cleaner UC may be used to clean the sensor surface SP3 of the comparison electrode SN3. Furthermore, the cleaning mechanism 101A may be configured so that all of the sensor surfaces SP1, SP2, and SP3 are cleaned using a liquid flow formed in the measurement target liquid LQ.

[0132] Other implementation methods are described below.

[0133] While an ammonia meter is used as an example of a liquid analyzer in the aforementioned embodiment, the present invention can be applied to any sensor having multiple sensor surfaces inclined relative to an extension axis, or to any device that analyzes a liquid. A more specific example of application is the application of the present invention to an ammonia meter having multiple sensors disposed within a single body, one of which is an ammonium ion electrode for measuring the potential generated by ammonium ions, and another of which is a sodium ion electrode for compensating for the effects of sodium ions in the target liquid on the ammonium ions. Another example of application is the application of the present invention to a liquid analyzer having one of which is a nitrate ion electrode for measuring the potential generated by nitrate ions, and another of which is a chloride ion electrode for compensating for the effects of chloride ions in the target liquid on the nitrate ions.

[0134] Furthermore, the present invention is applicable not only to sensors that measure the concentration of a single ion, but also to multi-purpose sensors that can simultaneously measure multiple electrochemical values ​​using a single liquid analyzer. Specific examples of multi-purpose sensors include those that incorporate a pH sensor, an ORP (oxidation-reduction potential) sensor, and a DO (dissolved oxygen) sensor into a single body.

[0135] The sensor may be not only one having a liquid junction or a response membrane formed on the sensor surface, but may also be an exposed electrode of an ISFET chip, etc. In short, the type of sensor is not particularly limited to the sensor shown in the above embodiment.

[0136] As a modified example of the insertion angle limiting structure, not only the radial shape of the sensor and the insertion hole can be utilized, but also the axial shape can be utilized to ensure that the sensor is fully engaged only when the sensor surface is facing the specified direction. The insertion angle limiting structure can also limit the insertion angle by utilizing the shape of the sensor and the engagement method of the through hole of the pressing mechanism. In short, the same effect can be obtained as long as the shape of the insertion hole illustrated in the embodiment is adapted to the through hole. In addition, the insertion angle limiting structure can also serve as an insertion error prevention structure at the same time. For example, as shown in the embodiment, the insertion angle limiting structure is constituted by a pin and an engagement groove, and by making their positions and numbers different, the function of the insertion error prevention structure can also be realized.

[0137] In addition, the present invention is not limited to the above-described embodiment, and various modifications are possible.

[0138] Industrial Applicability

[0139] According to the present invention, it is possible to provide a comparison electrode in which the time until potential fluctuation occurs is longer than that of conventional techniques, thereby maintaining measurement accuracy for a long period of time.

Claims

1. A comparative electrode, characterized in that include: The housing is cylindrical and has a liquid junction at the front end and is closed at the base end; an internal liquid filled in the shell; a tube housed in the housing and arranged to extend from the front end side to the base end side of the housing, the base end being arranged on the same side as the front end of the housing, the front end being arranged on the same side as the base end of the housing, the base end side of the tube being closed as the liquid junction side, and only the front end of the tube on the side opposite to the side where the internal electrode is arranged being open in the internal liquid, forming an opening for the internal liquid to enter the interior of the tube; and an internal electrode provided in the tube on the liquid junction side and arranged closer to the liquid junction than the opening; The tube is cylindrical, and only the internal electrode side space to which the internal electrode belongs is formed between the partition walls constituting the outer periphery of the tube. The tube is independent of the housing and is disposed in the existing housing so as to be away from the inner end surface of the base end side of the housing, and the opening of the tube is disposed as close as possible to the base end of the space inside the housing. The housing is a sealed housing that does not replenish the internal liquid. No opening that opens upward is formed on the base end side of the housing, and the space inside the housing is filled with the internal liquid without any gap.

2. The comparison electrode according to claim 1, characterized in that The tube is formed of any one of resin, glass, and ceramics.

3. The comparison electrode according to claim 1, wherein The internal liquid is in a gel state.

4. The comparison electrode according to claim 1, wherein The axial length of the housing is greater than the axial length of the tube.

5. An electrochemical measuring device, characterized in that include: The comparison electrode according to any one of claims 1 to 4; Measuring electrodes; an arithmetic unit for outputting measurement data representing a measurement result based on the output values ​​from the comparison electrode and the measurement electrode; as well as The main body mechanism is connected to the computing unit in a communicable manner and displays the measurement result in a predetermined manner based on the measurement data output from the computing unit.

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