JP7725757B1 - Residual chlorine meter - Google Patents

Abstract

[Problem] To improve measurement accuracy.
[Solution] The residual chlorine meter comprises a sensor body having a lower end that can be immersed in the measurement fluid during measurement, the sensor body having a measurement space provided at the lower end and connected to the outside through an opening, an intake port provided at the lower end, a pump chamber that introduces the measurement fluid through the intake port, an impeller provided in the pump chamber and driven to rotate, an outlet facing the measurement space and discharging the measurement fluid introduced into the pump chamber into the measurement space, and a discharge flow path connecting the pump chamber and the discharge port, a drive mechanism that drives the impeller to rotate, and a sensor head that has an electrode facing the outlet port in the measurement space and comes into contact with the measurement fluid to output an oxidation/reduction current based on the concentration of free residual chlorine contained in the measurement fluid, and the discharge flow path of the pump mechanism extends diagonally upward in a straight line from the pump chamber toward the electrode during measurement.
[Selected Figure] Figure 1

Description

The present invention relates to a residual chlorine meter.

One known reagentless method for measuring the concentration of free residual chlorine is the polarographic method (polarography). The polarographic method measures the oxidation/reduction current that flows between two electrodes (a counter electrode and a working electrode) immersed in the test water when a voltage (measurement voltage) is applied between the two electrodes. This allows the ion concentration of a specific chemical species to be measured.

Three-electrode polarographic methods are also known, which use a reference electrode (standard electrode) in addition to a counter electrode and working electrode. In three-electrode methods, a reference potential is applied to the reference electrode to determine the potential of the working electrode, whose absolute potential is unknown. This three-electrode polarographic method has the advantage of being resistant to changes in conductivity and allowing the electrodes to be made smaller. In polarographic methods, the oxidation/reduction current value changes when the flow rate of the test water in contact with the electrodes changes, so the electrodes must be in contact with a constant flow rate of test water.

An amperometric sensor system (see, for example, Patent Document 1) is known as an installed residual chlorine meter that uses this type of polarographic method. In this system, a sensor housing containing a chlorine sensor and a pH sensor is inserted directly into a joint or the like of a water distribution pipe. Test water is supplied to the electrodes of each sensor at a constant flow rate by a pump with an impeller driven by a magnetic coupling.

A portable residual chlorine meter that uses the Galvanic method, which differs from the polarographic method, is known as a residual chlorine measuring instrument (see, for example, Patent Document 2). The Galvanic method measures the oxidation-reduction current that flows between two electrodes without applying a voltage. In this residual chlorine measuring instrument, an impeller attached to a shaft that is directly connected to a motor and extends into the pump chamber is rotated, and the test water is transported from the pump chamber into a tube equipped with a residual chlorine concentration detection unit having a pair of electrode plates, thereby performing the measurement.

Furthermore, there is known a portable residual chlorine meter (see, for example, Patent Document 3) in which, in a preparation stage, a calibration coefficient is calculated using data for calculating the calibration coefficient based on the pre-calibration residual chlorine reaction amount of the test water and the calibration standard residual chlorine reference concentration, and in a measurement stage, the calibrated residual chlorine concentration of the test water is calculated using data for calculating the calibrated residual chlorine concentration based on the measurement residual chlorine reaction amount of the test water and the calibration coefficient.

US Patent Application Publication No. 2018/0143152 Japanese Utility Model Application Publication No. 61-178461 Patent No. 4377197

However, the system disclosed in Patent Document 1 has a complex water flow and uses cleaning beads, which means that there are factors that adversely affect the water flow, such as water reflection. This makes it difficult to improve measurement accuracy.

Furthermore, the measuring device disclosed in Patent Document 2 also requires the water flow to bend by 90 degrees, which causes reflection of the water and adversely affects the water flow. This makes it difficult to improve measurement accuracy.

Furthermore, with the residual chlorine meter disclosed in Patent Document 3, the sensor of the sensor unit must be immersed in the test water and stirred while measuring. This means that measurement accuracy is prone to variation, making it difficult to maintain a stable, high level of measurement accuracy.

The present invention was made in consideration of the above circumstances, and aims to provide a residual chlorine meter with high measurement accuracy.

The residual chlorine meter of the present invention comprises a sensor body with a lower end that can be immersed in the measurement fluid during measurement. The sensor body comprises a measurement space provided on the side of the lower end and connected to the outside via an opening; a pump mechanism having an inlet provided at the lower end, a pump chamber that introduces the measurement fluid through the inlet, a rotationally driven impeller provided in the pump chamber, an outlet facing the measurement space and discharging the measurement fluid introduced into the pump chamber into the measurement space, and a discharge flow path connecting the pump chamber and the discharge port; a drive mechanism that rotationally drives the impeller; and a sensor head that has an electrode facing the outlet in the measurement space and that contacts the measurement fluid to output an oxidation/reduction current based on the concentration of free residual chlorine contained in the measurement fluid. During measurement, the discharge flow path of the pump mechanism extends diagonally upward in a straight line from the pump chamber toward the electrode.

In one embodiment of the present invention, the discharge flow path of the pump mechanism extends obliquely upward in a straight line from the intersection with the discharge-side tangent to the rotational orbit of the impeller toward the electrode surface of the electrode during the measurement.

In another embodiment of the present invention, the sensor main body has a case member formed in a cylindrical shape extending in the vertical direction and having the opening, the pump mechanism is detachably attached to the lower end side of the case member and has a pump head in which the suction port, the pump chamber, the discharge flow path, and the discharge port are formed, and the drive mechanism is housed in the case member and includes a driven member provided at the base of the impeller, a drive member arranged opposite the driven member in the direction of the impeller's rotation axis and magnetically connected to the driven member to rotate the impeller, and a drive motor that rotates the drive member.

In yet another embodiment of the present invention, the sensor head includes a first columnar portion, a second columnar portion provided at one end of the first columnar portion and having a smaller diameter than the first columnar portion, a counter electrode and a reference electrode arranged parallel to the side surface of the first columnar portion, and multiple working electrodes arranged at the tip of the second columnar portion, and the discharge flow path of the pump mechanism extends from the pump chamber toward the multiple working electrodes.

This invention can improve measurement accuracy.

1 is a perspective view showing the appearance of a residual chlorine meter according to a first embodiment of the present invention; FIG. 2 is an exploded perspective view of the sensor body of the residual chlorine meter. FIG. 2 is a perspective view showing the configuration of a pump mechanism and a sensor head with a portion of the lower end of the sensor main body cut away. FIG. 2 is a view showing a lower end portion of the sensor main body with a portion thereof cut away. FIG. 2 is a perspective view showing the pump head removed from the case member. FIG. 2 is a perspective view of the impeller and its surroundings, with a portion cut away. FIG. 2 is a cross-sectional view of an impeller and a portion of its periphery. FIG. FIG. 2 is a perspective view showing the appearance of a sensor head. FIG. 2 is a block diagram for explaining a measurement circuit inside the controller. 10 is a diagram for explaining the connection state of the sensor main body and the controller during measurement. FIG. 10 is a diagram for explaining the connection state of the sensor main body and the controller when stored. FIG. 10A and 10B are diagrams illustrating examples of applied voltage and measured current in air/water detection. FIG. 2 is a perspective view illustrating the submerged area of the sensor body and the air storage area (air barrier area). 10A and 10B are diagrams illustrating modified examples of the impeller of the pump mechanism in the sensor main body. 10A and 10B are diagrams for explaining the discharge of air bubbles by the impeller.

Below, we will explain in detail the residual chlorine meter according to an embodiment of the present invention, with reference to the accompanying drawings. However, the following embodiments do not limit the inventions according to the claims, and not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention.

In the following embodiments, identical or equivalent components are designated by the same reference numerals, and redundant explanations are omitted. In addition, in the embodiments, the arrangement, scale, dimensions, etc. of each component may be exaggerated or minimized, and may not correspond to the actual components, and descriptions of some components may be omitted.

[Configuration of the residual chlorine meter of the first embodiment]
Fig. 1 is a perspective view showing the appearance of a residual chlorine meter according to a first embodiment of the present invention. Fig. 2 is an exploded perspective view of a sensor body of this residual chlorine meter. Fig. 1(a) shows the appearance of the residual chlorine meter as seen from above, and Fig. 1(b) shows the appearance of the sensor body as seen from above at a different angle.

As shown in FIG. 1(a), the residual chlorine meter 100 according to this embodiment comprises a sensor body 10 and a controller 20. For example, during measurement, the sensor body 10 is used with its longitudinal direction aligned with the vertical direction (up-down direction) so that its lower end is immersed in the measurement fluid (test water) containing chlorine. The controller 20 is provided separately from the sensor body 10 and is detachably attached to the top end of the sensor body 10 during measurement and to the side of the sensor body 10 when stored.

[Configuration of sensor main body 10]
The sensor main body 10 includes, for example, a cylindrical case member 11 extending in the vertical direction. The case member 11 is formed, for example, from a resin molded product formed so that the cross section is a chamfered triangular shape, specifically a chamfered isosceles triangle shape. As shown in FIG. 2 , the case member 11 has an opening 12 at its lower end. The case member 11 has an opening 13 in a part of a wall portion 14 near the lower end. The case member 11 has an internal measurement space 15 that is connected to the outside via the opening 13. In the following description, the side of the case member 11 on which the opening 13 is formed will be referred to as the "front side," and the opposite side will be referred to as the "rear side."

A mark 11b is formed on the side of the wall 14 of the case member 11 to indicate the submersion range, for example, the range in which the lower end of the sensor main body 10 can be immersed in the test water (measurement fluid). Furthermore, as shown in FIG. 1(b), an air outlet 6 is formed on the rear side of the wall 14 below this mark 11b. The air outlet 6 is located at the bottom of the air storage area (hereinafter referred to as the "air barrier area"), which will be described later. Furthermore, a second storage attachment portion 5, for example, with a T-shaped cross section, is formed on the wall 14 above this air outlet 6. The second storage attachment portion 5 slides into engagement with the first storage attachment portion 21 formed on the side of the controller 20.

The upper end of the case member 11 is also formed with a cable gland 19 to which the cable 29 of the controller 20 is attached, and a plate-shaped second measurement mounting portion 18 inclined at a predetermined angle that slides into engagement with a first measurement mounting portion 22 formed on the rear (back) side of the controller 20.

As shown in Figure 2, the sensor body 10 has a pump mechanism 50 on the rear side of the lower end, and a sensor head 70 on the front side of the lower end. The sensor body 10 also has a drive mechanism 60 above the pump mechanism 50 that drives the pump mechanism 50.

Figure 3 is an oblique view of the pump mechanism 50 and sensor head 70, with a portion of the lower end of the sensor body 10 cut away. Figure 3(a) is a view of the sensor body 10 seen from diagonally below, and Figure 3(b) is a view of the sensor body 10 seen from diagonally above. Figure 4 is a view of the lower end of the sensor body 10 with a portion cut away. Figure 4(a) is a view from the front of the lower end of the sensor body 10 with a portion cut away shown in Figure 3, and Figure 4(b) is a view of the same from the right side.

[Configuration of pump mechanism 50]
As shown in FIGS. 3 and 4, the pump mechanism 50 includes a pump head 30 and an impeller 40 that is attached to the pump head 30 and driven to rotate.

The pump head 30 is made of, for example, a resin molded part and has a pump chamber 31 formed with an upwardly extending circular recess. The bottom surface of the pump head 30 is provided with an inlet 32 through which the measurement fluid is introduced into the pump chamber 31 from below the sensor body 10. The inlet 32 is configured, for example, with multiple slits to prevent foreign matter in the test water from entering the pump chamber 31. The pump head 30 has a discharge flow path 33 that extends diagonally upward in a straight line from the pump chamber 31 toward the sensor head 70 during measurement, and a discharge port 34 that is the outlet of the discharge flow path 33 on the sensor head 70 side. As shown in Figure 4(a) , the discharge flow path 33 also extends diagonally upward toward the sensor head 70 when viewed from the front. More specifically, during measurement, the discharge flow path 33 extends diagonally upward in a straight line from the intersection (point of intersection) of the rotational orbit of the impeller 40 and the discharge-side tangent to the rotational orbit toward the sensor head 70.

Figure 5 is a perspective view showing the pump head 30 removed from the case member 11. The pump head 30 is removably attached to the opening 12 at the bottom of the case member 11. Specifically, as shown in Figure 5, operating sections 39 with engaging claws 38 are provided on both sides of the underside of the pump head 30, and the pump head 30 is attached to the case member 11 by engaging the engaging claws 38 with engaging holes 14a provided on both sides of the bottom of the case member 11. Pressing the operating sections 39 from both sides disengages the engaging claws 38 from the engaging holes 14a. This eliminates the need for additional fastening parts such as bolts and nuts to attach the pump head 30 to the case member 11, reducing the weight and cost of the sensor main body 10 and making it easier to attach and detach the pump head 30.

Figure 6 is a perspective view with a portion of the impeller 40 and its surrounding area cut away. Figure 7 is a cross-sectional view of the impeller 40 and its surrounding area. Figure 7(a) is a front view of the impeller 40 and its surrounding area cut away, and Figure 7(b) is a right side view of the same.

The impeller 40 has a plurality of blades 43 arranged on the pump chamber 31 side, a base 41 on which the plurality of blades 43 are formed, a driven magnet 61 which is a driven member provided on the base 41, and a lid 42 which secures the driven magnet 61 to the base 41. The base 41 and lid 42 of the impeller 40 are made, for example, of a resin molded product. The base 41 of the impeller 40 is formed, for example, in a cylindrical shape. The base 41 and lid 42 are secured together, for example, by ultrasonic welding or adhesive bonding.

The driven magnet 61 built into the base 41 of the impeller 40 is composed of, for example, a neodymium magnet formed in a circular ring shape. The lid 42 of the impeller 40 has a stepped, disc-like outer shape. The lid 42 is configured as a stopper that can secure the driven magnet 61 to the base 41.

The impeller 40 also has, for example, a conical portion 44 located between the base 41 and the multiple blades 43. As shown in Figures 7(a) and 7(b), the conical portion 44 serves to allow air (bubbles) 8 generated around the multiple blades 43 to escape upward along the inclined, curved surface.

The pump mechanism 50 further includes, for example, an impeller support portion 51 that rotatably supports the impeller 40 on the rotation shaft. The impeller 40 is disposed within the pump chamber 31 of the pump head 30 while being rotatably supported on the rotation shaft by this impeller support portion 51.

Figure 8 shows the impeller support part 51, where Figure 8(a) is a perspective view, Figure 8(b) is a front view of Figure 8(a) viewed from the direction of arrow F, Figure 8(c) is a cross-sectional view of Figure 8(b) cut along line A-A and viewed from the direction of the arrows, Figure 8(d) is an enlarged cross-sectional view of part B in Figure 8(c), Figure 8(e) is a side view of Figure 8(a) viewed from the direction of arrow G, and Figure 8(f) is an enlarged view of part C in Figure 8(e).

As shown in Figures 6 to 8, the impeller support portion 51 has a cylindrical housing portion 52 that houses the drive magnet 62 and one end of the motor shaft 63. The impeller support portion 51 also has a disk-shaped support member 53 provided at the tip end of the housing portion 52. The impeller support portion 51 also has a hook-shaped arm member 54 that extends from the outer peripheral edge of the support member 53 along the rotational axis direction of the impeller 40 and is bent at its tip end in a direction intersecting the rotational axis direction.

The main portion of this impeller support part 51 is disposed within the measurement space 15 of the case member 11. The accommodation section 52 of the impeller support part 51 is formed in a cylindrical shape and is disposed within the measurement space 15 adjacent to the sensor head 70. A first support protrusion 53a is provided at the center of the support member 53 of the impeller support part 51. A second support protrusion 54a is provided at the tip of the arm member 54. The first support protrusion 53a and the second support protrusion 54a are disposed opposite each other along the rotation axis of the impeller 40.

Meanwhile, a central recess is formed in the engaging protrusion 42a formed in the center of the lid portion 42 of the impeller 40, and in the tip portion 45 of the impeller 40. These central recesses engage with the first support protrusion 53a and the second support protrusion 54a, thereby sandwiching the impeller 40 in the direction of the rotation axis and rotatably supporting it. The impeller 40 can be easily attached to and detached from the impeller support portion 51 by utilizing the flexibility of the arm member 54.

Furthermore, as shown in FIG. 8(a), the support member 53 of the impeller support portion 51 has an air extraction mechanism 55 that expels air that accumulates above the impeller 40 upward. The air extraction mechanism 55 includes at least one (two, in this example) recessed portion 53c that widens from the first support protrusion 53a side toward the outer periphery on the surface 53b of the support member 53 that faces the bottom surface (surface of the lid portion 42) of the base portion 41 of the impeller 40 in the rotational axis direction.

The air bleed mechanism 55 also includes a slit 53d at the outer peripheral end of the recess 53c, which narrows in diameter from the recess 53c upward. The recess 53c has a tapered bottom surface 53e that slopes upward from the first support protrusion 53a toward the outer periphery.

[Configuration of drive mechanism 60]
2 and 6, the drive mechanism 60 has a driven magnet 61 provided on the base 41 of the impeller 40. The drive mechanism 60 also has a drive magnet 62 disposed opposite the driven magnet 61 in the direction of the rotation axis of the impeller 40 and connected to the driven magnet 61 in a non-contact manner by magnetic coupling.

The drive mechanism 60 further includes a motor shaft 63 connected to the drive magnet 62, and a drive motor 64 connected to the end of the motor shaft 63 opposite the drive magnet 62, and which drives the drive magnet 62 to rotate via the motor shaft 63. The drive motor 64 is, for example, a DC motor.

The drive magnet 62 and motor shaft 63 of the drive mechanism 60 constitute the drive member. This drive member and drive motor 64 are housed in the storage space 16 at the top of the case member 11, as shown in Figure 2. The storage space 16 is liquid-tightly separated from the measurement space 15. An opening 11a is formed in the wall 14 of the case member 11 at a position corresponding to the storage space 16. A cover 17 is attached to this opening 11a via a gasket 16a made of various sealing materials such as rubber or elastomer. As a result, the storage space 16 is sealed off from the outside, as the opening 11a is liquid-tightly closed.

This opening 11a serves as an access port for the sensor main body 10 to the drive mechanism 60 and other components located within the housing space 16 of the case member 11. The cover 17 is configured to be detachable from the opening 11a, for example, by a locking mechanism having an engagement structure (not shown) for engaging with the engaged portion 16b provided within the housing space 16.

[Configuration of sensor head 70]
3 and 4, the sensor head 70 is disposed in the measurement space 15 so as to be exposed from the opening 13 of the case member 11. The electrodes of the sensor head 70 come into contact with the measurement fluid discharged from the pump chamber 31, and the sensor head 70 outputs an oxidation/reduction current based on the concentration of free residual chlorine contained in the measurement fluid.

The sensor head 70 is made of, for example, a resin molded part. The sensor head 70 is detachably attached to a head mounting portion 70a (see Figure 2) provided on the impeller support portion 51. The sensor head 70 is positioned adjacent to the housing portion 52 of the impeller support portion 51 within the measurement space 15.

Figure 9 is a perspective view showing the appearance of the sensor head 70. As shown in Figure 9, the sensor head 70 has, for example, a first columnar portion 71 formed in a cylindrical shape and a second columnar portion 72 formed in an elliptical cylindrical shape with a smaller diameter than the first columnar portion 71. Note that the shapes of the first columnar portion 71 and the second columnar portion 72 are not limited to these cylindrical and elliptical cylindrical shapes, and various shapes can be adopted.

This sensor head 70 further includes a temperature sensor 76 for measuring the temperature of the test water, which is disposed adjacent to the second columnar section 72. The sensor head 70 also includes electrodes in contact with the fluid to be measured, such as a counter electrode 73 and a reference electrode (standard electrode) 74 arranged parallel to the side of the first columnar section 71, and multiple working electrodes 75a, 75b arranged at the tip of the second columnar section 72.

The counter electrode 73 and reference electrode 74 are each linear electrodes arranged on the opening 13 side of the wall 14 of the case member 11. The counter electrode 73 is made of, for example, gold or platinum. The reference electrode 74 is made of, for example, silver or gold. Each of the multiple working electrodes 75a, 75b has a circular electrode surface facing the measurement space 15 above the discharge port 34 of the pump head 30. The working electrode 75a is made of, for example, gold. The working electrode 75b is made of, for example, platinum.

In this way, by using different materials for the multiple working electrodes 75a, 75b, the residual chlorine meter 100 of the first embodiment can accommodate multiple types of chlorine agents in test water. For example, the gold working electrode 75a is suitable for use with test water such as sodium hypochlorite, which has low electrical conductivity and therefore cannot be used with platinum. For this reason, the gold working electrode 75a is used, for example, when measuring the concentration of free residual chlorine in test water containing sodium hypochlorite that is diluted and used as is, acidified and used to increase its disinfecting power, or diluted and heated to a high temperature.

Furthermore, for example, the platinum working electrode 75b is suitable for use with test water such as electrolyzed water, which contains a large amount of salt and would dissolve if gold were used. For this reason, the platinum working electrode 75b is used, for example, as a test water for electrolyzed water (hypochlorous acid water), when measuring the concentration of free residual chlorine in slightly acidic electrolyzed water, weakly acidic electrolyzed water, strongly acidic electrolyzed water, electrolyzed water (alkaline), and electrolyzed water to which acidic chemicals have been added.

Other chlorine agents include calcium hypochlorite and sodium dichloroisocyanurate. These working electrodes 75a and 75b are used depending on the chlorine agent in the measured fluid. The materials for the working electrodes 75a and 75b are not limited to those mentioned above, and various materials can be used. Furthermore, the working electrodes 75a and 75b may each have a construction in which the gold and platinum mentioned above are interchanged.

The working electrodes 75a and 75b are formed in a flat (disk-like) shape because the measured concentration varies depending on their surface area. On the other hand, the counter electrode 73 and reference electrode 74 are made of inexpensive wire, since their size does not affect their performance as long as the surface area of the counter electrode 73 is not too small. Furthermore, the counter electrode 73 and reference electrode 74 are provided on the side of the sensor head 70 because they do not need to come into contact with the measurement fluid at a specified flow rate.

[Configuration of controller 20]
As shown in Figure 1 (a), the controller 20 of the residual chlorine meter 100 of the first embodiment has a case portion 28 formed in a shape that can be held in one hand by a user (measurer), a monitor display (hereinafter referred to as the "monitor") 23 provided on the front (surface) side of the case portion 28 and displaying various information, and an operation button portion 24 for operating the information displayed on the monitor 23, including the operation of the sensor main body 10.

The monitor 23 of the controller 20 functions as a notification unit capable of notifying various types of information, including information related to the results of the air/water detection described below. The controller 20 may also be equipped with a speaker (not shown) or lamps capable of audio output as a notification unit. The operation button unit 24 of the controller 20 includes various operation buttons, such as a power ON/OFF button, cursor button, enter button, back button, brightness adjustment button, and measurement start button.

The controller 20 also includes, inside the case 28, a power supply unit (not shown) equipped with a power source such as a dry cell battery, and a control unit (not shown) that controls the entire sensor body 10, including the operation of the pump mechanism 50 of the sensor body 10 and measurements by the sensor head 70. The control unit of the controller 20 applies a drive voltage (e.g., 1.5 V) from the power supply unit to the drive motor 64 using, for example, a PWM voltage application method.

As a result, the drive motor 64 rotates the motor shaft 63 and drive magnet 62 at a constant rotation speed, which in turn keeps the rotation speed of the impeller 40 constant via the driven magnet 61. Therefore, the measurement fluid discharged from the pump chamber 31 through the discharge flow path 33 and discharge port 34 can be transported at a constant flow rate and flow rate, which are essential for highly stable measurement accuracy.

FIG. 10 is a block diagram for explaining the measurement circuit inside the controller.
10 , the control unit of the controller 20 includes, for example, a measurement circuit 80 and an applied voltage generation unit 86. The measurement circuit 80 includes switches 81a and 81b, a current-voltage conversion circuit 82, a voltage amplifier 83, a microcomputer 84, a display unit 23a, and a memory unit 85. For example, if the working electrode 75a of the sensor head 70 is designated as sensor 1 and the working electrode 75b is designated as sensor 2, the switches 81a and 81b connect either sensor 1 or sensor 2 to the current-voltage conversion circuit 82. These switches 81a and 81b are configured, for example, by photoMOS relays. When measurement is stopped, both switches 81a and 81b are turned OFF.

The measurement current, which is the oxidation/reduction current from sensor 1 or sensor 2, is converted to a voltage value by current-voltage conversion circuit 82 via switch 81a or switch 81b, amplified by voltage amplifier 83, and input to microcomputer 84. Based on the input voltage value, microcomputer 84 calculates the concentration of free residual chlorine in the measurement fluid, outputs the measurement result indicating the calculated value to display unit 23a, and stores it in memory unit 85.

The display unit 23a controls the display of the monitor 23, displaying various information such as measurement results on the display screen. The measurement results are stored in the memory unit 85 so that they can be read after each measurement. This eliminates the need for the user (the person taking the measurement) to take notes on the measurement results, further improving convenience.

The applied voltage generating unit 86 includes a DAC 87 that performs digital-to-analog conversion of an applied voltage control signal from the microcomputer 84, a voltage amplifier 88 that amplifies an applied voltage (such as a measurement voltage) from a power supply unit according to the value converted by the DAC 87, and a reference voltage generating unit 89 that generates a reference voltage to be applied to the reference electrode 74. During initial cleaning, the applied voltage generating unit 86 applies a predetermined pulsed applied voltage (cleaning voltage) for initial cleaning, which is different from the measurement voltage, to the counter electrode 73 of the sensor head 70, for example. The cleaning voltage is applied by, for example, repeating pulses of a predetermined duration multiple times. During normal measurement, the applied voltage generating unit 86 applies a measurement voltage to the counter electrode 73 of the sensor head 70, for example.

[Connection configuration between sensor main body 10 and controller 20]
Fig. 11 is a diagram for explaining the connection state of the sensor main body 10 and the controller 20 during measurement. Fig. 11(a) is a perspective view showing the state of the sensor main body 10 and the controller 20 before connection during measurement, and Fig. 11(b) is a perspective view showing the state of the sensor main body 10 and the controller 20 after connection during measurement. Fig. 12 is a diagram for explaining the connection state of the sensor main body 10 and the controller 20 when stored. Fig. 12(a) is a perspective view showing the state of the sensor main body 10 and the controller 20 before connection during storage, and Fig. 12(b) is a perspective view showing the state of the sensor main body 10 and the controller 20 after connection during storage.

In the first embodiment of the residual chlorine meter 100, the sensor body 10 and the controller 20 are configured as separate, detachable components. This not only makes it highly portable, but also provides the following additional features: As shown in Figure 11(a), before the two are connected during measurement, the sensor body 10 and the controller 20 are not integrated.

The second measurement mounting portion 18 provided at the upper end of the case member 11 of the sensor main body 10 and the first measurement mounting portion 22 formed on the back side of the controller 20 are slid into engagement in the direction indicated by the double arrow in the figure. As a result, as shown in Figure 11(b), as is clear from the state after the two are connected during measurement, the controller 20 is connected and integrated at an angle relative to the sensor main body 10 at the upper end of the sensor main body 10, whose longitudinal direction extends vertically.

Therefore, during measurement, the user (measurer) can perform the measurement by immersing the lower end of the sensor body 10 vertically in the test water within the submersion range, while holding the controller 20 in one hand and checking the monitor 23.

At this time, the opening 13 on the front side of the sensor body 10 faces the user (measurer), making it possible to easily check the state of the measurement fluid discharge side and perform measurements, for example, while avoiding contact with the liquid. In this way, the user (measurer) can use the residual chlorine meter 100 with one hand during measurement, making it possible to perform measurements while performing other tasks, such as taking notes, with the other hand.

Therefore, the residual chlorine meter 100 of the first embodiment can easily measure the concentration of free residual chlorine without, for example, needing to fix the sensor body 10 to a flow cell (measurement tank) or the like. In this way, the residual chlorine meter 100 can easily perform measurements regardless of the measurement environment, making it extremely convenient.

On the other hand, as shown in Figure 12(a), before the two are connected during storage, the sensor main body 10 and controller 20 are not integrated, but the second storage mounting portion 5 provided on the side of the wall portion 14 of the case member 11 of the sensor main body 10 and the first storage mounting portion 21 provided on the side of the controller 20 slide together in the direction indicated by the double arrow in the figure.

As a result, as shown in Figure 12(b), and as is clear from the state after the two are connected when stored, the controller 20 is connected alongside the sensor main body 10 and integrated with it on the side of the sensor main body 10, whose longitudinal direction extends vertically as described above.

As a result, when stored, the sensor main body 10 and controller 20 can be stored compactly as a single integrated device, rather than being separated from each other. This is advantageous in that the residual chlorine meter 100 can be transported particularly easily, increasing convenience.

[Operation of residual chlorine meter 100]
Next, the operation of the residual chlorine meter 100 of the first embodiment will be described.
First, the user (measurer) sets the sensor body 10 and controller 20 to the state after connection during measurement shown in Fig. 11(b). Next, while holding the controller 20, the user immerses the submerged area of the sensor body 10 vertically in the test water and turns the power on by pressing the power on/off button on the operation button section 24 of the controller 20. Next, the user selects either the working electrode 75a or 75b using the switches 81a, 81b (Fig. 10).

[Initial cleaning]
FIG. 13 is a diagram showing an example of applied voltage and measured current in air/water detection.
When either the working electrode 75a or 75b is selected by the switch 81a or 81b, the working electrode 75a or 75b is initially cleaned before each measurement. The initial cleaning of the electrode is performed by outputting an applied voltage control signal from the microcomputer 84 of the measurement circuit 80 to the applied voltage generator 86, as shown in FIG.

That is, the applied voltage generating unit 86 performs digital-to-analog conversion of the applied voltage control signal from the microcomputer 84 using the DAC 87, and amplifies the applied voltage (measurement voltage, etc.) from the power supply unit according to the converted value using the voltage amplifier 88. Then, during initial cleaning, the applied voltage generating unit 86 applies a predetermined pulsed cleaning voltage for initial cleaning that is different from the measurement voltage (e.g., greater than the measurement voltage) to the counter electrode 73 of the sensor head 70, as shown in FIG. 13. The cleaning voltage is, for example, a pulsed voltage that lasts for 10 seconds at a cycle of 0.5 seconds.

At this time, the sensor current (measurement current) flowing between the counter electrode 73 of the sensor head 70 and one of the working electrodes 75a, 75b is converted into a voltage value by the current-voltage conversion circuit 82 of the measurement circuit 80 as described above, amplified by the voltage amplifier 83, and input to the microcomputer 84. The microcomputer 84 then performs threshold determination using, for example, thresholds 1 and 2 as shown in the figure.

Based on the results of this threshold determination by the microcomputer 84, empty water detection of the sensor head 70 of the sensor main body 10 is performed. In other words, this empty water detection automatically determines whether the sensor head 70 is in the test water during initial cleaning before the actual measurement begins. If the current value of the measurement current exceeds either threshold 1 or 2 (or both) for example a predetermined number of times, the microcomputer 84 determines that the sensor head 70 is in the test water and continues measurement, for example after initial cleaning.

On the other hand, if the current value of the measured current does not exceed both thresholds 1 and 2, for example, for a predetermined number of times, the microcomputer 84 determines that the sensor head 70 is in the air. In this case, the microcomputer 84 may display information on the display screen of the monitor 23, for example, via the display unit 23a, indicating that the sensor head 70 is not in the sample water and therefore cannot be measured correctly.

In addition, based on the information on the determination results by the microcomputer 84, the control unit can forcibly stop the rotation of the impeller 40 by the drive mechanism 60, for example, if it determines that the sensor head 70 is in the air. In this way, by stopping the rotation of the impeller 40 when the sensor head 70 is in the air, it is possible to extend the life of the sensor main body 10 by preventing the impeller 40 from spinning freely in the air, which would otherwise result in wasted power consumption, and by suppressing heat generation caused by the operation of the pump mechanism 50 and drive mechanism 60 around the impeller 40.

[During normal measurement]
The measurement operation is initiated when the microcomputer 84 determines that the lower end of the sensor body 10 is immersed in the sample water. The concentration of free residual chlorine is measured by applying a measurement voltage to the counter electrode 73 for a predetermined time (e.g., 15 seconds) and detecting an oxidation/reduction current from one of the working electrodes 75 a, 75 b.

In this state, when the impeller 40 of the pump mechanism 50 is rotationally driven by the drive mechanism 60, the measurement fluid is introduced from the suction port 32 of the pump head 30 into the pump chamber 31 in the fluid suction direction indicated by the dotted arrow 35 in the figure, as shown in FIG. 4. The rotation of the impeller 40 causes the measurement fluid introduced into the pump chamber 31 to pass through the discharge flow path 33 from within the pump chamber 31 along the fluid discharge direction indicated by the dotted arrow 36 in the figure, and then discharged obliquely upward from the discharge port 34 toward the sensor head 70. The measurement fluid discharged from the discharge port 34 comes into contact with the working electrodes 75a, 75b of the sensor head 70 at a predetermined flow rate, and is then discharged outside the measurement space 15 through the opening 13 in the wall 14.

In this way, in the sensor body 10 of the residual chlorine meter 100, the measurement fluid can be applied to the sensor head 70 at an angle when viewed from the front and side within the measurement space 15, and then drained directly from the measurement space 15 to the outside. This prevents reflection of the measurement fluid, which could affect the measurement of the concentration of free residual chlorine in the test water, and prevents turbulence in the flow of the measurement fluid that comes into contact with the working electrodes 75a and 75b, resulting in a constant, smooth flow.

Furthermore, as shown in Figures 7(a) and 7(b), the air bleed mechanism 55 provided on the support member 53 of the impeller support portion 51 has the function of releasing air 8 generated around the impeller 40 rotating in the pump chamber 31 within the measurement space 15 above the support member 53. In other words, the air 8 generated around the blades 43 of the impeller 40 flows along the sloping curved surface of the conical portion 44 to the upper side of the base 41 and escapes through the air bleed flow path 9a indicated by the dotted arrow in the figure.

Furthermore, air 8 that accumulates on the surface 53b of the support member 53 above the base 41 moves along the bottom surface 53e of the recess 53c toward the slit 53d, and then escapes upward through the slit 53d and the air escape channel 9b indicated by the dotted arrow in the figure. In this way, the air extraction mechanism 55 allows the air 8 around the impeller 40 to escape upward, preventing increased power consumption due to rotational friction caused by the presence of air pockets.

FIG. 14 is a perspective view for explaining the submerged area and air storage area (air barrier area) of the sensor body 10.
14(a) and 14(b) show partially cutaway top perspective views of the sensor main body 10, respectively, viewed from different directions. As shown in FIGS. 14(a) and 14(b), the upper peripheral edge of the impeller support portion 51 within the measurement space 15 of the case member 11 is connected to the inner surface of the case member 11. A waterproof seal is applied between the upper peripheral edge of the impeller support portion 51 and the inner surface of the case member 11, for example, by means of caulking 7 made of silicone or the like. This prevents the measurement fluid from penetrating from the measurement space 15 side into the accommodation space 16 above it in the case member 11.

The air 8 released upward by the air extraction mechanism 55 gradually accumulates around the periphery of the storage section 52 and above the measurement space 15, forming an air layer between the measurement space 15 and the storage space 16. This air layer becomes the air barrier region. Any air 8 that cannot be stored within this air barrier region is discharged into the test water from the air outlet 6, which is located below the upper end of the submerged range of the sensor body 10.

In the sensor body 10, this air barrier region blocks the path of fluid infiltration into the accommodation space 16. In other words, the impeller support part 51 in the measurement space 15 is waterproofed by the caulking 7 described above, but the air layer in the air barrier region also prevents the caulking 7 from coming into direct contact with the measurement fluid during measurement.

Furthermore, after measurement, the submerged area of the case member 11 of the sensor body 10 is washed with running water from above, so theoretically the measured fluid does not come into contact with the caulking 7, effectively preventing deterioration of the caulking 7 due to corrosion caused by the measured fluid.

In addition, in the sensor body 10, these air barrier areas and caulking 7 provide double waterproofing for the housing space 16 of the case member 11 when viewed from the measurement space 15 side. This prevents, for example, the measurement fluid from entering the housing space 16 from the measurement space 15 side during measurement, and the drive mechanism 60 and other components within the housing space 16 are completely isolated from the measurement space 15 side that comes into contact with the test water.

Even if the caulking 7 is damaged, the drive motor 64 of the drive mechanism 60 is physically located within the housing space 16 above the submerged area of the sensor body 10, via an air barrier area, so the structure is able to minimize malfunctions caused by water ingress.

[Modification of the first embodiment]
Fig. 15 is a diagram illustrating a modified example of the impeller of the pump mechanism 50 in the sensor main body 10. Fig. 16 is a diagram illustrating the discharge of air bubbles by the impeller. Fig. 15(a) shows a side view of the impeller, and Fig. 15(b) shows a plan view of the impeller.

As shown in Figures 15(a) and 15(b), the impeller 40A of a modified pump mechanism 50 differs from the previous impeller 40 in the structure of the blades 43. That is, each blade 43 of the impeller 40A has an inclined surface 43a formed on the surface opposite to the surface in the impeller rotation direction R, as indicated by the arrow in the figure.

This inclined surface 43a forms, for example, a spherical curved surface that gradually widens and changes in inclination angle from the tip 45 to the base 41 of the blade 43 of the impeller 40A. This prevents the impeller 40A from rotating with air bubbles attached to the blade 43 of the impeller 40A, causing the air bubbles to become trapped and unable to escape due to negative pressure. Note that the inclined surface 43a is not limited to a curved surface and may also be a flat surface.

In other words, one of the causes of air bubble entrainment is thought to be convection that occurs on the side opposite to the surface of the blade 43 in the rotation direction R that scrapes out the fluid, so the inclined surface 43a suppresses convection. Furthermore, air bubble entrainment can also occur due to low wettability based on the material, so the surfaces of each blade 43 and conical portion 44 may be textured.

As a result, as shown in FIG. 16, air bubbles Ab generated around the impeller 40A are effectively discharged from the pump chamber 31 along the discharge path Ep that passes through the discharge flow path 33 and the discharge port 34 as the impeller 40A rotates. Therefore, by using this impeller 40A in conjunction with the air extraction mechanism 55 described above, it is possible to more effectively release air 8 and air bubbles Ab to the upper side of the measurement space 15. Note that while the above-described impellers 40 and 40A are illustrated as having three blades 43 spaced approximately 120° apart circumferentially around the rotation axis, the multiple blades 43 can also be configured with two blades 43 spaced approximately 180° apart circumferentially around the rotation axis in order to reduce the number of locations where negative pressure occurs and make it easier for air bubbles to escape.

[Effects of the first embodiment]
In the first embodiment, when the normal to the electrode surfaces of the working electrodes 75a, 75b of the sensor head 70 is parallel to the rotational axis direction of the impeller 40, if the discharge flow path 33 of the pump mechanism 50 is provided in the tangential direction on the discharge side of the rotational orbit of the impeller 40, it is necessary to either make the discharge flow path 33 horizontal and position the electrode surfaces of the working electrodes 75a, 75b at the same height as the discharge port, or to bend the discharge flow path 33 at a right angle toward the electrode surfaces of the working electrodes 75a, 75b. In the former case, the measurement fluid will be reflected by the side surface of the sensor head 70, while in the latter case, reflection will occur at the right-angle bent portion and the electrode surfaces of the working electrodes 75a, 75b. In either case, turbulence will occur in the flow of the measurement fluid.

In this regard, according to the first embodiment, the discharge flow path 33 from the pump chamber 31 to the electrode surfaces of the working electrodes 75a and 75b extends in a straight line diagonally upward from the intersection of the rotational orbit of the impeller 40 and the discharge-side tangent line toward the electrode surfaces of the working electrodes 75a and 75b. This prevents reflection of the measurement fluid, which is harmful to measurement, within the discharge flow path 33 and on the surface of the sensor head 70. Furthermore, since the measurement fluid that reaches the sensor head 70 is discharged to the outside through the opening 13, reflection by the case member 11 also does not occur. This allows for a smooth flow of the measurement fluid, improving measurement accuracy.

In addition, the shape and structure of the impeller 40 and the structure of the air extraction mechanism 55 allow air and bubbles trapped around the impeller 40 to be effectively released upward. This prevents an increase in power consumption by the drive mechanism 60, which is magnetically coupled to the impeller 40.

In addition, the drive mechanism 60, including the drive motor 64, is housed in a waterproof housing space 16 above the submerged area within the measurement space 15 of the sensor body 10, and an air barrier area is formed between the measurement space 15 and the housing space 16, which, together with the caulking 7, prevents the measurement fluid from entering the housing space 16.

In addition, since the sensor body 10 is not constantly immersed in the test water, simply removing the sensor head 70 after measurement and cleaning the electrode surface keeps the electrode surface clean. This eliminates the need to use beads or other cleaning tools to clean the electrode surface, making maintenance such as cleaning easier. Furthermore, since beads or other tools are not required, the measurement space 15 can be made open. Furthermore, since the pump head 30 can be attached and detached from the sensor body 10 without using fastening parts, and the impeller 40 and other parts can be replaced, foreign matter that has entered the measurement space 15 can be easily removed.

In addition, in the first embodiment, during the initial cleaning prior to normal measurement, the current value flowing between the counter electrode 73 and the working electrodes 75a, 75b is detected, and the empty water state is detected based on whether a predetermined current flows. This makes it possible to detect an empty water state (a state where the electrode is not submerged) during the initial cleaning, and to stop or prevent pump operation in an empty water state early before the start of measurement operation.

The residual chlorine meter 100 is also highly convenient, as it can be easily used with one hand regardless of the measurement environment. It also offers excellent portability, as the sensor body 10 and controller 20 can be easily connected and disconnected with one hand during measurement and when storing the device for transport.

The above describes an embodiment of the present invention, but this embodiment is presented as an example and is not intended to limit the scope of the invention. This novel embodiment can be embodied in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims.

5 Second storage mounting portion 10 Sensor body 11 Case member 12, 13 Opening 14 Wall portion 15 Measurement space 16 Storage space 18 Second measurement mounting portion 20 Controller 21 First storage mounting portion 22 First measurement mounting portion 30 Pump head 31 Pump chamber 32 Suction port 33 Discharge flow path 34 Discharge port 40, 40A Impeller 43 Blade 44 Conical portion 50 Pump mechanism 51 Impeller support portion 52 Storage portion 53 Support member 54 Arm member 55 Air bleeding mechanism 60 Drive mechanism 61 Follower magnet 62 Drive magnet 70 Sensor head 73 Counter electrode 74 Reference electrode (standard electrode)
75a, 75b Working electrode 80 Measuring circuit 100 Residual chlorine meter

Claims (4)

a sensor body having a lower end that can be immersed in the measurement fluid during measurement;
The sensor body includes:
a measurement space provided at the lower end portion and connected to the outside via an opening;
a pump mechanism including a suction port provided at the lower end, a pump chamber into which the measurement fluid is introduced via the suction port, an impeller provided in the pump chamber and driven to rotate, a discharge port facing the measurement space and discharging the measurement fluid introduced into the pump chamber into the measurement space, and a discharge flow path connecting the pump chamber and the discharge port;
a drive mechanism that rotationally drives the impeller;
a sensor head including an electrode facing the discharge port in the measurement space, the electrode coming into contact with the measurement fluid and outputting an oxidation/reduction current based on the concentration of free residual chlorine contained in the measurement fluid;
and
The residual chlorine meter, wherein the discharge flow path of the pump mechanism extends obliquely upward in a straight line from the pump chamber toward the electrode during the measurement. The residual chlorine meter according to claim 1 , wherein the discharge flow path of the pump mechanism extends obliquely upward in a straight line from an intersection with a discharge-side tangent to the rotational orbit of the impeller toward the electrode surface of the electrode during the measurement. The sensor body includes:
a case member formed in a cylindrical shape extending in the vertical direction and having the opening,
The pump mechanism includes:
a pump head that is detachably attached to a lower end side of the case member and that has the suction port, the pump chamber, the discharge flow path, and the discharge port formed therein;
The drive mechanism includes:
A residual chlorine meter as described in claim 1, comprising: a driven member housed in the case member and provided at the base of the impeller; a drive member arranged opposite the driven member in the direction of the rotational axis of the impeller and magnetically connected to the driven member to rotate the impeller; and a drive motor for rotating the drive member. The sensor head includes:
A first columnar portion;
a second columnar portion provided at one end of the first columnar portion and having a smaller diameter than the first columnar portion;
a counter electrode and a reference electrode arranged parallel to a side surface of the first columnar portion;
a plurality of working electrodes disposed at the tips of the second pillars;
and
The residual chlorine meter according to claim 1 , wherein the discharge flow path of the pump mechanism extends from the pump chamber toward the plurality of working electrodes.