JP7127580B2 - Oxygen concentration measuring device and oxygen concentration measuring method - Google Patents

Description

The present invention relates to an oxygen concentration measuring device and an oxygen concentration measuring method.

A sensor is used to detect the concentration of a component contained in a gas. For example, Patent Literature 1 discloses obtaining the concentration of hydrogen gas contained in a gas to be measured by using a heat flow sensor and a pressure sensor. Further, Patent Document 2 discloses an invention relating to gas concentration measurement using ultrasonic waves.

JP 2017-90317 A Japanese Patent Application Laid-Open No. 2006-275608

By the way, in the oxygen concentrator, nitrogen contained in the atmosphere is removed by a predetermined filter in order to concentrate oxygen contained in the atmosphere. However, it is conceivable that the percentage of oxygen contained in the enriched gas that has passed through the filter will relatively decrease as the performance of the filter deteriorates over time. Therefore, in order to easily grasp the time to replace the filter, the technology disclosed in Patent Documents 1 and 2 (hereinafter simply referred to as conventional technology) is used to reduce the oxygen contained in the concentrated gas after passing through the filter. It is conceivable to measure the concentration.

Here, it is conceivable that the concentrated gas that has passed through the filter contains three or more components such as oxygen, nitrogen, and argon. Therefore, it is conceivable to measure the physical properties of concentrated gases with various oxygen concentrations by a conventional technique, and store in advance the correspondence between the oxygen concentrations and the measured values of the physical properties. Then, it is conceivable to measure the physical properties of the concentrated gas to be measured, and obtain the concentration of oxygen corresponding to the measured physical property values by referring to the previously stored correspondence relationship.

However, in the case of such a method, it is considered that the load for creating the correspondence relationship between the oxygen concentration of the concentrated gas and the physical property value is large. In particular, if there is little regularity in the change in the physical properties of the concentrated gas with respect to the change in the component ratio, it is necessary to change the component ratio more finely and create the corresponding relationship, which increases the above load. That is, the present inventors have found that the sensor disclosed in Patent Documents 1 and 2 requires a load when measuring the component concentration of a concentrated gas containing three or more components, so the concentration of oxygen concentrated in an oxygen concentrator cannot be easily measured, and therefore it is not possible to easily grasp the timing of replacement of the filter that removes nitrogen.

In one aspect, the present invention has been made in view of such circumstances, and an object of the present invention is to easily measure the concentration of oxygen contained in oxygen-enriched gas in an oxygen concentrator. It is to provide technology.

The present invention adopts the following configurations in order to solve the above-described problems.

That is, an oxygen concentration measuring device according to one aspect of the present invention is an oxygen concentration measuring device that measures the concentration of oxygen after concentration in an oxygen concentrator, and is an oxygen concentration measuring device that removes nitrogen contained in the air and concentrates the oxygen. a heating unit that heats the concentrated gas in which oxygen is concentrated by means; an output unit that is arranged across the heating unit and performs an output based on the temperature of the concentrated gas; a thermal conductivity calculator that calculates the thermal conductivity of the gas; and an oxygen concentration calculator that calculates the concentration of oxygen contained in the enriched gas with respect to the thermal conductivity of the enriched gas calculated by the thermal conductivity calculator. wherein the enriched gas includes an initially enriched gas in which oxygen has been enriched by the oxygen enrichment means in an initial state when the use of the oxygen enrichment means is started, and air that has permeated the oxygen enrichment means. , the oxygen concentration calculator calculates the thermal conductivity and oxygen concentration of the enriched gas based on the thermal conductivity and oxygen concentration in the initial enriched gas and the thermal conductivity and oxygen concentration in the air. An oxygen concentration measuring device characterized by calculating the concentration of oxygen.

According to this configuration, the concentrated gas to be measured is the initial concentrated gas in which oxygen is concentrated by the oxygen concentrating means in the initial state when the use of the oxygen concentrating means is started, and the air that has permeated the oxygen concentrating means (hereinafter referred to as , permeated air). Here, the initially concentrated gas is a gas composed of oxygen concentrated by removing nitrogen contained in the air by the oxygen concentrating means and argon contained in the air before concentration. Also, the air that has passed through the oxygen concentrating means is air from which nitrogen has not been removed by the oxygen concentrating means, and contains at least three components of oxygen, nitrogen, and argon.

Here, the component ratio of concentrated oxygen and argon contained in the initially concentrated gas does not depend on the amount of permeated air, and is substantially constant. Therefore, the thermal conductivity of the initially enriched gas is substantially constant. In other words, the relationship between the thermal conductivity of the initial enrichment gas and the concentration of the enriched oxygen contained in the initial enrichment gas is substantially constant, so it only needs to be determined once, and should be determined again when the amount of permeated air changes. can be done without

On the other hand, the component ratio of oxygen, nitrogen, and argon contained in the permeated air is substantially the same as the component ratio of the air before nitrogen is removed by the oxygen concentrating means. In other words, the relationship between the thermal conductivity of the permeated air and the concentration of oxygen contained in the permeated air is the relationship between the thermal conductivity of the air existing in the installation environment of the oxygen concentrator and the concentration of oxygen contained in the air. . Therefore, the relationship can be determined in advance before measuring the concentration of oxygen in the enriched gas, and is a substantially constant relationship.

Therefore, according to this configuration, it is possible to calculate the oxygen concentration of the enriched gas with respect to the thermal conductivity of the enriched gas based on the thermal conductivity and oxygen concentration of the initial enriched gas and the thermal conductivity and oxygen concentration of the permeated air. . In addition, the oxygen concentration calculation unit does not need to store in advance the correspondence relationship of the thermal conductivity of the enriched gas with respect to various concentrations of oxygen contained in the enriched gas. That is, according to this configuration, the concentration of oxygen contained in the concentrated gas can be easily measured in the oxygen concentrator.

Moreover, according to this configuration, the distribution of heat generated by heating by the heating unit changes when the concentrated gas flows. Therefore, the output from the output section changes depending on whether the concentrated gas flows or not. Also, the magnitude of the change in output from the output section is related to the magnitude of the flow rate of the concentrated gas. Therefore, according to this configuration, the flow rate of the concentrated gas can also be calculated from the output from the output unit. That is, according to this configuration, the flow rate of the enriched gas can be measured in addition to the component ratio of the enriched gas containing at least three components. That is, this configuration is a compact device with low manufacturing cost because it can measure the component ratio and the flow rate of the concentrated gas with a single device.

In the oxygen concentration measuring device according to the above aspect, the oxygen concentration calculator calculates the thermal conductivity of the initially concentrated gas as λ _a , the oxygen concentration as C _a , and the thermal conductivity of the air that has passed through the oxygen concentrator as Let λ _b be the oxygen concentration, let C _b be the oxygen concentration, let λ _x be the thermal conductivity of the enriched gas calculated by the thermal conductivity calculator, and let C _x be the oxygen concentration of the enriched gas. may be characterized by calculating _Cx by

According to this configuration, the concentration of oxygen contained in the concentrated gas can be easily calculated by substituting the thermal conductivity of the concentrated gas calculated by the thermal conductivity calculation unit into the calculation formula.

In the oxygen concentration measuring device according to the above aspect, the oxygen concentration calculation unit calculates the thermal conductivity when changing the existence ratio of the initially concentrated gas and the air that has passed through the oxygen concentrating means in the concentrated gas. The oxygen concentration of the enriched gas may be calculated with reference to the correspondence relationship between the thermal conductivity and the oxygen concentration in the enriched gas, which is calculated based on the values of the oxygen concentration and the oxygen concentration.

According to this configuration, the oxygen concentration calculation unit can calculate the concentration of oxygen contained in the concentrated gas based on the corresponding relationship with respect to the thermal conductivity of the concentrated gas calculated by the thermal conductivity calculation unit. .

In the oxygen concentration measuring device according to the above aspect, the correspondence relationship is such that as the proportion of air that has passed through the oxygen enrichment means contained in the enriched gas increases, the concentration The concentration of oxygen contained in the gas may include a monotonically changing relationship.

According to the configuration, the oxygen concentration calculation unit calculates the concentration of oxygen contained in the concentrated gas on a one-to-one basis based on the corresponding relationship with respect to the thermal conductivity of the concentrated gas calculated by the thermal conductivity calculation unit. be able to.

The oxygen concentration measuring device according to the above aspect may further include measuring means for measuring the concentration of oxygen contained in the air and the thermal conductivity of the air.

According to this configuration, even if the composition of the air itself existing in the environment where the oxygen concentrator is installed changes due to a change in the environment where the oxygen concentration measuring device is installed, and the ratio of the components of the permeated air changes. , the change may be measured by a measuring means and the measurement of the change may be used to calculate the oxygen concentration of the enriched gas. That is, according to this configuration, the oxygen concentration of the concentrated gas in the oxygen concentrator can be measured with high accuracy regardless of changes in the environment in which the oxygen concentration measuring device is installed.

The present invention can also be viewed from a method aspect. That is, an oxygen concentration measuring method according to one aspect of the present invention is an oxygen concentration measuring method for measuring the concentration of oxygen after concentration in an oxygen concentrator, wherein nitrogen contained in air is removed and oxygen is concentrated. a thermal conductivity calculation step of calculating the thermal conductivity of a concentrated gas in which oxygen is concentrated by the enrichment means; an oxygen concentration calculation step of calculating the concentration of oxygen contained in the concentrated gas with respect to the thermal conductivity of the concentrated gas; and the enriched gas includes an initial enriched gas in which oxygen has been enriched by the oxygen enrichment means in an initial state when the use of the oxygen enrichment means is started, and air that has passed through the oxygen enrichment means. , in the oxygen concentration calculating step, based on the thermal conductivity and oxygen concentration in the initial enriched gas and the thermal conductivity and oxygen concentration in the air, It may be an oxygen concentration measuring method characterized by calculating the concentration of oxygen contained in the gas.

In the oxygen concentration measuring method according to the above aspect, in the oxygen concentration calculating step, the thermal conductivity of the initially concentrated gas is λ _a , the oxygen concentration is C _a , and the thermal conductivity of the air that has passed through the oxygen concentrating means is is λ _b , the oxygen concentration is C _b , the thermal conductivity of the enriched gas calculated in the thermal conductivity calculation step is λ _x , and the oxygen concentration of the enriched gas is C _x , the formula (1 ) to calculate _Cx .

In the oxygen concentration measuring method according to the above aspect, in the oxygen concentration calculating step, in the enriched gas, heat conduction when changing the existence ratio of the initially enriched gas and the air that has passed through the oxygen enrichment means The oxygen concentration of the enriched gas may be calculated with reference to the correspondence relationship between the thermal conductivity and the oxygen concentration in the enriched gas, which is calculated from the values of the thermal conductivity and the oxygen concentration.

ADVANTAGE OF THE INVENTION According to this invention, it is an oxygen concentrator. WHEREIN: The technique which can measure simply the density|concentration of the oxygen contained in the gas in which oxygen was concentrated can be provided.

FIG. 1 schematically illustrates an example of an overview of oxygen concentration measurement by an oxygen concentration measuring device according to an embodiment. FIG. 2 illustrates an example of an equivalent circuit showing that heat generated from the heater is transferred to the thermopile. FIG. 3 is an example illustrating the relationship between the thermopile output and the thermal conductivity of the mixed gas. FIG. 4 schematically illustrates an example of the outline of the relationship between the thermal conductivity of the mixed gas and the oxygen concentration contained in the mixed gas. FIG. 5 schematically illustrates an example of an overview of measurement of oxygen concentration contained in mixed gas according to the prior art. FIG. 6 schematically illustrates an example of an outline of a functional block diagram of the oxygen concentration measuring device. FIG. 7 schematically illustrates an example of an overview of changing the component ratio of oxygen and nitrogen contained in the mixed gas and determining constants. FIG. 8 schematically illustrates an example schematic for measuring the oxygen concentration of the earliest oxygen-enriched gas and the thermal conductivity of the earliest oxygen-enriched gas. FIG. 9 schematically illustrates an example of a flow chart showing the processing procedure of the oxygen concentration measuring device. FIG. 10 schematically illustrates an example of an outline of an oxygen concentration measuring device.

Hereinafter, an embodiment (hereinafter also referred to as "this embodiment") according to one aspect of the present invention will be described based on the drawings. However, this embodiment described below is merely an example of the present invention in every respect. It goes without saying that various modifications and variations can be made without departing from the scope of the invention. That is, in implementing the present invention, a specific configuration according to the embodiment may be appropriately employed.

§1 Application Example An example of a scene to which the present invention is applied will be described with reference to FIGS. 1 and 2. FIG. FIG. 1 schematically illustrates an example of an overview of oxygen concentration measurement by an oxygen concentration measuring device 1 according to this embodiment. As shown in FIG. 1, the oxygen concentration measuring device 1 detects the concentration of oxygen contained in the mixed gas passing through the flow tube member 2 . Here, the mixed gas is the gas that has flowed in from the outside of the oxygen concentrator and has passed through the filter 3 that adsorbs nitrogen. The mixed gas contains at least oxygen and argon contained in the outside air, and nitrogen that has not been removed by adsorption in the filter 3 .

Further, as shown in FIG. 1 , the oxygen concentration measuring device 1 includes a substrate 4 and a thin film 5 mounted on the substrate 4 . The oxygen concentration measuring device 1 has a heater 6 arranged in the center of the thin film 5 . The heater 6 heats the mixed gas gently passing over it. The oxygen concentration measuring device 1 also has thermopiles 7 A and 7 B on both sides of the heater 6 . The thermopiles 7A and 7B output according to the temperature difference between their ends.

FIG. 2 illustrates an example of a heat equivalent circuit showing that heat generated from the heater 6 is transmitted to the thermopile 7A. The heat emitted from the heater 6 is carried by the mixed gas and reaches the contacts 8 and 9 of the thermopile 7A. Here, it is considered that the heat transferred from the contact 8 to the contact 9 via the mixed gas is constantly added with thermal resistance that depends on the composition ratio of the mixed gas. In other words, when the component ratio contained in the mixed gas changes and the thermal resistance of the mixed gas changes, the temperature difference between the temperature of the contact 8 and the temperature of the contact 9 also changes. Therefore, the ratio of components contained in the mixed gas is detected from the output of the thermopile 7A.

In this embodiment, the mixed gas that has changed due to deterioration of the filter 3 over time is converted into the oxygen-enriched gas in the earliest stage where the filter 3 is newly installed and the nitrogen is removed as desired to concentrate the oxygen. The evaluation is made assuming that the gas is mixed with the outside air that has passed through it.

Here, the physical properties of the oxygen-enriched gas at the earliest stage do not change even with aging. Therefore, the thermal conductivity of the oxygen-enriched gas at the earliest stage is substantially constant regardless of aging. That is, the thermal conductivity of the oxygen-enriched gas at the earliest stage and the concentration of the enriched oxygen contained in the oxygen-enriched gas at the earliest stage may be determined once immediately after the filter 3 is installed.

In addition, the component ratio of the outside air and the physical properties of the outside air do not change even after aging in the same manner. Therefore, the thermal conductivity of the outside air and the concentration of oxygen contained in the outside air can be measured in advance before measuring the concentration of oxygen in the mixed gas to be measured.

In other words, in the present embodiment, changes in physical properties of the entire mixed gas to be measured over time are not due to changes in the physical properties of the oxygen-enriched gas and the physical properties of the outside air at the earliest stage, but the amount of outside air mixed into the mixed gas monotonically changes. It is due to an increase in Therefore, the correspondence relationship between the concentration of oxygen contained in the entire mixed gas and the thermal conductivity of the entire mixed gas is a relationship including monotonous changes. Therefore, according to the oxygen concentration measuring device 1, the thermal conductivity of the mixed gas to be measured is calculated, and the calculated thermal conductivity of the mixed gas is calculated based on the corresponding relationship of the oxygen contained in the mixed gas. Concentration can be easily calculated on a one-to-one basis. As a result, it is possible to easily grasp when the filter 3 needs to be replaced.

§2 Configuration example [Hardware configuration]
Next, an example of the oxygen concentration measuring device according to this embodiment will be described. As shown in FIG. 1, an oximetry device 1 is contained in a mixed gas that is gently passed through a flow tube member 2 provided inside an oxygen concentrator used, for example, by a patient suffering from a respiratory disease. Detects oxygen concentration. Here, the mixed gas is the gas that has flowed in from the outside of the oxygen concentrator and has passed through the filter 3 that adsorbs nitrogen. The mixed gas contains at least oxygen contained in the outside air, nitrogen not removed by adsorption in the filter 3, and argon.

Further, as shown in FIG. 1 , the oxygen concentration measuring device 1 includes a substrate 4 and a thin film 5 mounted on the substrate 4 . The oxygen concentration measuring device 1 has a heater 6 covered with a thin film 5 . The heater 6 heats the mixed gas passing over it. Here, the heater 6 is an example of the "heating part" of the present invention.

The oxygen concentration measuring device 1 also has thermopiles 7 A and 7 B on both sides of the heater 6 . The thermopiles 7A and 7B output according to the temperature difference between their ends. The substrate 4 also has a cavity 20 in which the heater 6 is arranged and which opens toward the thin film. Due to the existence of the cavity 20 , heat distribution occurs in the space near the heater 6 . Here, the thermopiles 7A and 7B are an example of the "output section" of the present invention.

Here, since the flow of the mixed gas passing above the thermopiles 7A and 7B is slow, the output from the thermopiles 7A and 7B is the output when the flow of the mixed gas is almost stopped.

In the example shown in FIG. 1, the thermopile 7A and the thermopile 7B are arranged side by side in the direction of flow of the mixed gas. may be provided.
[Thermal conductivity measurement principle]

As shown in FIG. 2, the heat emitted from the heater 6 reaches the thermopile 7A through the thin film 5. As shown in FIG. Here, assuming that R _s is the thermal resistance of the thin film, it is considered that R _s is constantly added to the heat that moves through the thin film 5 . Also, the heat reaching the contact 8 on one side of the thermopile 7A with the thin film 5 reaches the contact 9 on the opposite side through the thermopile 7A. Assuming that the thermal resistance of the thermopile is _Rt , _Rt is considered to be constantly added to the heat that reaches the contact 9 from the contact 8 through the thermopile 7A.

On the other hand, unlike the thin film 5, the heat emitted from the heater 6 is also carried by the mixed gas and reaches the contacts 8 and 9 of the thermopile 7A. Here, assuming that the thermal resistance of the mixed gas is R _g , it is considered that the heat transferred from the contact 8 to the contact 9 through the mixed gas is steadily added with R _g .

That is, the temperature difference ΔT between the temperature of the contact 8 and the temperature of the contact 9 of the thermopile 7A is expressed by the following equation (2), where I is the amount of heat generated by the heater.

Therefore, by measuring ΔT, the thermal resistance R _g can be obtained from the equation (2). Here, the thermal resistance R _g is a value corresponding to the component ratio of the mixed gas. Also, thermal resistance and thermal conductivity are in an inversely proportional relationship. Therefore, by measuring ΔT, the thermal conductivity of the mixed gas can be obtained.

FIG. 3 is an example illustrating the relationship between the output of the thermopile 7A (corresponding to ΔT described above) and the thermal conductivity λ of the mixed gas. If the constants a, b, and c of the following approximation formula (3) that fit the relationship between the output x of the thermopile 7A shown in FIG. 3 and the thermal conductivity λ of the mixed gas are determined in advance, oxygen Even when a mixed gas having an unknown component ratio of .beta. and nitrogen flows through the flow tube member 2, the thermal conductivity .lambda.
λ=ax ² +bx+c (3)

[Oxygen concentration measurement principle]
In this embodiment, the mixed gas that has passed through the filter 3 is the oxygen-enriched gas in which the filter 3 is newly installed and nitrogen is removed as desired, and the oxygen is concentrated. It is considered that the gas is mixed with outside air that has passed through the filter 3 without nitrogen being removed due to a decrease in nitrogen adsorption efficiency. In other words, immediately after the filter 3 is installed, it is assumed that the nitrogen adsorption performance of the filter 3 has not deteriorated. Think of it as a small gas. On the other hand, when the filter 3 is installed and a predetermined period of time has passed, it is assumed that the nitrogen adsorption performance of the filter 3 has deteriorated. think there is. Here, the mixed gas is an example of the "concentrated gas" of the present invention. Also, the initial oxygen-enriched gas is an example of the "initial enrichment gas" of the present invention. Also, outside air is an example of "air that has passed through the oxygen concentrator" in the present invention. Moreover, the filter 3 is an example of the "oxygen concentrator" of the present invention.

The earliest oxygen-enriched gases include oxygen and argon, desirably enriched. The concentration of oxygen contained in the initial oxygen-enriched gas is, for example, 96%. In addition, outside air is the air existing in the environment where the oxygen concentrator is installed, and includes oxygen, nitrogen, and argon. Then, the component ratio of the outside air can be obtained in advance before measuring the mixed gas.

Here, C _a is the concentration of concentrated oxygen contained in the oxygen-enriched gas at the earliest stage, λ _a is the thermal conductivity of the oxygen-enriched gas at the earliest stage, C _b is the concentration of oxygen contained in the outside air, and the heat of the outside air is Let λ _b be the conductivity, λ _x be the thermal conductivity when the initial oxygen-enriched gas is mixed with outside air at a rate of (1−x)%, and C _x be the concentration of oxygen. 4), Equation (5) holds.
λx= _xλa +(1− _x ) _λb (4)
C _x = x C _a + (1−x) C _b (5)

Also, the relationship between C _x and λ _x is as shown in Equation (1) from Equations (4) and (5).

Here, in the present embodiment, the oxygen concentration contained in the mixed gas and the thermal conductivity of the mixed gas immediately after the filter 3 is attached are measured, and these values are respectively C _a and λ _a of the initial oxygen-enriched gas. It is said that _Ca is measured by an oxygen concentration meter provided separately from the oxygen concentration measuring device 1 . Also, λ _a is calculated from the output of the thermopile 7A as shown in the above equations (2), (3), and FIGS. 2-3. Moreover, since C _a and λ _a are substantially constant regardless of deterioration of the filter 3 over time, it is only necessary to measure once immediately after the filter 3 is attached.

On the other hand, Cb and _λb of the outside air can be measured in advance before measuring the mixed gas to be measured, and the relationship between _Cb and _λb is _a substantially constant relationship. That is, the oxygen concentration measuring device 1 according to the present embodiment measures _Ca and _λ Equation (1) can be constructed only by measuring, and then when the mixed gas to be measured is flowed through the flow tube member 2, the concentration of oxygen contained in the mixed gas is calculated using Equation (1) from the output of the thermopile 7A can be calculated. That is, in order to measure the concentration of oxygen contained in the mixed gas, it is not necessary to store in advance the correspondence relationship of the thermal conductivity of the mixed gas with respect to various oxygen concentrations.

Also, FIG. 4 schematically illustrates an example of an overview of the relationship between the thermal conductivity λ _x of the mixed gas and the oxygen concentration C _x contained in the mixed gas. In this embodiment, the aging change in the physical properties of the entire mixed gas to be measured is not due to changes in the physical properties of the oxygen-enriched gas and the external air at the earliest stage, but due to an increase in the amount of external air mixed in the mixed gas. become a thing. Therefore, as shown in FIG. 4, the thermal conductivity λ _x of the entire mixed gas increases as the amount of outside air (permeated air) mixed in the mixed gas increases (the oxygen concentration C _x contained in the entire mixed gas is high to low), resulting in a monotonically decreasing correspondence. Here, the correspondence relationship shown in FIG. 4 is such that the thermal conductivity of the enriched gas and the thermal conductivity of the enriched gas increase as the proportion of air permeating through the oxygen enrichment means contained in the enriched gas increases. The concentration of oxygen is an example of "relationship that changes monotonously". Then, the corresponding relationship is the concentrated oxygen concentration C _a contained in the oxygen-enriched gas at the earliest stage, the thermal conductivity λ _a of the oxygen-enriched gas at the earliest stage, the oxygen concentration C b contained in the outside air, and the oxygen concentration C _b of the outside air. This relationship is determined when the thermal conductivity _λb is determined.

Then, the correspondence between the thermal conductivity λ _x of the mixed gas and the oxygen concentration C _x contained in the mixed gas as shown in FIG. 4 is stored in advance as table information, and based on the table information, the measurement target The oxygen concentration of the object to be measured can be calculated from the thermal conductivity of the mixed gas. Here, as the amount of outside air mixed in the mixed gas increases, the physical properties of the mixed gas monotonically decrease However, even if the physical properties of the mixed gas monotonically increase as the amount of outside air mixed into the mixed gas increases, the components contained in the mixed gas corresponding to the physical properties of the mixed gas measured in the same manner can be determined one-to-one.

FIG. 5 schematically illustrates an example of an overview of measurement of oxygen concentration contained in mixed gas according to the prior art. As shown in FIG. 5, even if the mixed gas contains three or more components and the ratio is unknown, the mixed gas ratio at that time can be changed by changing the air mixing ratio for each product, and the physical properties of the mixed gas (sonic velocity, thermal conductivity, etc.) ) and the oxygen concentration can be linked to the oxygen concentration and physical properties. That is, the correspondence relationship as shown in FIG. Concentration can be calculated. However, in the present invention, the relationship between the thermal conductivity λ _x of the mixed gas and the oxygen concentration C _x contained in the mixed gas is theoretically derived as shown in Equation (1) and FIG. On the other hand, in the prior art, as shown in FIG. 5, the correspondence relationship is merely obtained by actual measurement. Therefore, in the prior art, a load is required to obtain the oxygen concentration contained in the mixed gas.

[Function configuration]
Next, the functional configuration of the oxygen concentration measuring device 1 will be described. FIG. 6 schematically illustrates an example of an outline of a functional block diagram of the oxygen concentration measuring device 1. As shown in FIG.

The oxygen concentration measuring device 1 includes a control section 10 . The control unit 10 is formed of, for example, a CPU (Central Process Unit) and a storage device such as a ROM (Read Only Memory) or a RAM (Random Access Memory). The control unit 10 sets the constant a of Equation (3) that fits the relationship between the output x of the thermopile 7A when the component ratio of oxygen and nitrogen contained in the mixed gas is changed and the thermal conductivity λ of the mixed gas, b and c are determined in advance prior to measuring the oxygen concentration of the mixed gas to be measured. FIG. 7 schematically illustrates an example of an overview of determining constants a, b, and c by changing the component ratio of oxygen and nitrogen contained in the mixed gas. As shown in FIG. 7, nitrogen gas and oxygen gas each flow into separate flow tubes. Each flow tube is provided with an MFC (Mass Flow Controller) to adjust the flow rates of nitrogen and oxygen. The nitrogen gas and oxygen gas whose flow rates have been adjusted are then combined to form a mixed gas and flow to one flow tube member 2A. The oxygen concentration measuring device 1 is provided in the flow tube member 2A, and the output of the thermopile 7A when the mixed gas flows is obtained. Also, the thermal conductivity of the mixed gas is measured by a known sensor. The constants a, b, and c are adjusted so that the equation (3) fits the measurement data of the output and thermal conductivity λ of the thermopile 7A thus obtained.

In addition, when measuring the oxygen concentration of the mixed gas to be measured, the control unit 10 determines the thermal conductivity of the mixed gas from the output of the thermopile 7A and the equation (3) including the previously obtained constants a, b, and c. Calculate Further, the control unit 10 calculates the oxygen concentration of the mixed gas to be measured from the calculated thermal conductivity of the mixed gas to be measured and Equation (1). Here, the control unit 10 is an example of the "thermal conductivity calculation unit" and the "oxygen concentration calculation unit" of the present invention. Further, the control unit 10 applies a predetermined voltage to the heater 6 to generate heat.

The oxygen concentration measuring device 1 also includes a measuring unit 11 . The measurement unit 11 has a sensor unit 12 . The sensor unit 12 acquires outputs from the thermopiles 7A and 7B provided in the flow tube member 2. FIG.

The oxygen concentration measuring device 1 also includes a first storage unit 13 . The first storage unit 13 stores the values of the constants a, b, and c of the above equation (3).

The oxygen concentration measuring device 1 also includes a second storage unit 14 . The second storage unit 14 stores the oxygen concentration C _a of the oxygen-enriched gas at the earliest stage and the thermal conductivity λ _a of the oxygen-enriched gas at the earliest stage. FIG. 8 schematically illustrates an example of a schematic for measuring the oxygen concentration C _a of the earliest oxygen-enriched gas and the thermal conductivity λ _a of the earliest oxygen-enriched gas. As shown in FIG. 8, the mixed gas that passed through the filter 3 and the oxygen concentration measuring device 1 immediately after the filter 3 was attached to the oxygen concentrator was measured by a known thermal conductivity measurement sensor, and the measured thermal conductivity Let be the thermal conductivity λ _a of the initial oxygen-enriched gas. Also, the concentration of oxygen contained in the mixed gas is measured by _a known oxygen concentration meter, and the measured oxygen concentration is taken as the oxygen concentration Ca of the oxygen-enriched gas at the earliest stage. Here, the initial thermal conductivity λ _a of the oxygen-enriched gas may be calculated using the output of the thermopile 7A and equation (3) instead of the measurement by the thermal conductivity measurement sensor.

The second storage unit 14 also stores the oxygen concentration _Cb of the outside air and the thermal conductivity _λb of the outside air. The oxygen concentration _Cb of the outside air and the thermal conductivity _λb of the outside air are the oxygen concentration and the thermal conductivity of the air in the environment where the oxygen concentrator is installed, so they are measured in advance before measuring the mixed gas.

The oxygen concentration measuring device 1 also includes an input unit 15 . The input unit 15 receives known information necessary for calculating the concentration of oxygen contained in the mixed gas from the output of the thermopile 7A. For example, information such as the thermal conductivity of the air in the environment where the oxygen concentrator is installed (thermal conductivity λ _b of outside air) and the concentration of oxygen contained in the air (oxygen concentration C _b of outside air).

The oxygen concentration measuring device 1 also includes an output unit 16 . If the oxygen concentration measuring device 1 is provided with a display (for example, a display), the output unit 16 displays the calculated concentration of oxygen contained in the mixed gas on the display.

§3 Operation Example Next, an operation example of the oxygen concentration measuring device 1 will be described. FIG. 9 schematically illustrates an example of a flowchart showing the processing procedure of the oxygen concentration measuring device 1. As shown in FIG. Note that the processing procedure described below is merely an example, and each processing may be changed as much as possible. Further, in the processing procedures described below, steps can be omitted, replaced, and added as appropriate according to the embodiment.

(Step S101)
In step S<b>101 , the air that has flowed in from the outside of the oxygen concentrator passes through the filter 3 . Air contains at least three components: oxygen, nitrogen, and argon. Nitrogen is removed from the air as it passes through the filter 3 . Air from which nitrogen has been removed (mixed gas to be measured) then flows inside the flow tube member 2 . In the flow tube member 2 , a predetermined voltage is applied to the heater 6 by the controller 10 , and heat is distributed in the vicinity of the heater 6 . Then, the mixed gas to be measured passes through the portion where the heat distribution occurs. Then, the sensor unit 12 acquires the outputs of the thermopiles 7A and 7B while the mixed gas to be measured is flowing.

Also, the input unit 15 receives input of known information necessary for calculating the concentration of oxygen contained in the mixed gas from the output of the thermopile 7A. The information that is accepted is, for example, the thermal conductivity λ _b of the outside air and the oxygen concentration C _b of the outside air. The input thermal conductivity λ _b of the outside air and the oxygen concentration C _b contained in the outside air are stored in the second storage unit 14 . Also, the oxygen concentration C _a of the oxygen-enriched gas at the earliest stage and the thermal conductivity λ _a of the oxygen-enriched gas at the earliest stage are previously measured and input as described above. The oxygen concentration C _a of the oxygen-enriched gas at the earliest stage and the thermal conductivity λ _a of the oxygen-enriched gas at the earliest stage are similarly stored in the second storage unit 14 . The values of the constants a, b, and c in equation (3) are also determined before measurement of the mixed gas to be measured and stored in the first storage unit 13 as described above.

(Step S102)
In step S102, the control unit 10 uses the obtained output of the thermopile 7A, the constants a, b, and c stored in the first storage unit 13, and the formula (3) to determine the thermal conductivity of the mixed gas to be measured. Calculate λ _x .

(Step S103)
In step S103, the control unit 10 controls the calculated thermal conductivity of the mixed gas to be measured, the oxygen concentration C _a of the oxygen-enriched gas at the earliest stage stored in the second storage unit 14, and the oxygen-enriched gas at the earliest stage. The concentration C _x of oxygen contained in the mixed gas to be measured is calculated from the thermal conductivity λ _a of the outside air, the oxygen concentration C _b of the outside air, the thermal conductivity λ _b of the outside air, and the equation (1).

Here, without using the formula (1), the second storage unit stores in advance the correspondence relationship between the thermal conductivity λ _x of the mixed gas and the oxygen concentration C _x contained in the mixed gas as shown in FIG. It may be stored as table information, and the controller 10 may calculate the calculated thermal conductivity λ _x of the mixed gas and the oxygen concentration C _x of the mixed gas from the table information.

(Step S104)
In step S104, the oxygen concentration calculated by the output unit 16 is displayed to the outside via the display unit.

[Action/effect]
According to the oxygen concentration measuring device 1 as described above, the mixed gas to be measured is the oxygen-enriched gas in which the filter 3 is newly installed and the nitrogen is removed as desired and the oxygen is concentrated, and the outside air Consider a gas consisting of Here, the component ratio of oxygen and argon in the initial oxygen-enriched gas does not depend on the amount of outside air and is substantially constant. Therefore, the initial thermal conductivity λ _a of the oxygen-enriched gas is approximately constant. That is, the relationship between the thermal conductivity λ _a of the oxygen-enriched gas at the earliest stage and the concentration _Ca of the oxygen-enriched gas contained in the oxygen-enriched gas at the earliest stage is substantially constant, and only needs to be obtained once. is changed without having to ask again.

On the other hand, the component ratios of oxygen, nitrogen, and argon contained in the outside air are substantially the same as the component ratio of the air before nitrogen is removed by the filter 3 . In other words, the relationship between the thermal conductivity _λb of the outside air and the concentration _Cb of oxygen contained in the outside air is the relationship between the thermal conductivity of the air existing in the installation environment of the oxygen concentrator and the concentration of oxygen contained in the air. become. Therefore, the relationship can be obtained in advance before measuring the oxygen concentration _Cx of the mixed gas to be measured, and is a substantially constant relationship.

Therefore, according to the oxygen concentration measuring device 1, the thermal conductivity λ _{a of the oxygen-enriched gas at the earliest stage, the concentration C a of the enriched oxygen contained in the oxygen-enriched gas at the earliest stage, the thermal conductivity λ b of the} outside air, and the concentration _Cb of oxygen contained in the outside air can be obtained prior to the measurement of the mixed gas to be measured, and formula (1) can be constructed. Then, the thermal conductivity λ _x of the mixed gas to be measured is substituted into Equation (1), and the concentration C _x of oxygen contained in the mixed gas can be easily calculated.

Further, according to the oxygen concentration measuring device 1, the thermal conductivity λ _{a of the oxygen-enriched gas at the earliest stage, the concentration C a of the enriched oxygen contained in the oxygen-enriched gas at the earliest stage, the thermal conductivity λ b of the} outside air, and the concentration Cb of oxygen contained in the outside air can be obtained before measurement of the mixed gas to be measured, and table information including the monotonically changing correspondence shown in _FIG . 4 can be stored. Then, the concentration C _x of oxygen contained in the mixed gas is calculated one-to-one with respect to the thermal conductivity λ _x of the mixed gas to be measured by referring to the table information.

That is, the above-described oxygen concentration measuring apparatus 1 can measure the oxygen concentration of the mixed gas to be measured without storing in advance the correspondence relationship of the thermal conductivity of the mixed gas with respect to various concentrations of oxygen contained in the mixed gas. Concentration C _x can be calculated. That is, according to the oxygen concentration measuring device 1 as described above, in the oxygen concentrator, it is possible to easily measure the concentration of oxygen contained in the oxygen-enriched mixed gas that has passed through the filter 3 . Therefore, it is possible to easily grasp when the filter 3 needs to be replaced.

Further, according to the oxygen concentration measuring device 1 as described above, the distribution of heat generated by the heating by the heater 6 changes when the mixed gas flows. Therefore, the outputs from the thermopiles 7A and 7B change depending on whether the mixed gas flows or not. Also, the magnitude of the change in output from the thermopiles 7A and 7B is related to the flow rate of the mixed gas. Therefore, according to the oxygen concentration measuring device 1 described above, the flow rate of the mixed gas can also be calculated from the outputs from the thermopiles 7A and 7B. That is, according to the oxygen concentration measuring device 1 as described above, the flow rate of the mixed gas can be measured in addition to the component ratio of the mixed gas containing at least three components of oxygen, nitrogen, and argon. That is, the oxygen concentration measuring device 1 described above can measure the component ratio and the flow rate of the mixed gas with a single device, and thus is a compact device with low manufacturing cost.

§4 Modifications Although the embodiments of the present invention have been described in detail, the above description is merely an example of the present invention in every respect. It goes without saying that various modifications and variations can be made without departing from the scope of the invention. For example, the following changes are possible. In addition, below, the same code|symbol is used about the component similar to the said embodiment, and description is abbreviate|omitted suitably about the point similar to the said embodiment. The following modified examples can be combined as appropriate.

<4.1>
In the above embodiment, the outside air is the air in the environment where the oxygen concentrator is installed, so the oxygen concentration C _b of the outside air and the thermal conductivity λ _b of the outside air are obtained before measuring the oxygen concentration contained in the mixed gas. was measurable and the information was entered via the input unit 15 prior to measuring the oxygen concentration. However, the installation environment of the oxygen concentrator may change, and the component ratio of the air in the installation environment may change. Alternatively, the physical properties of the air in the installation environment of the oxygen concentrator may be unknown, and the oxygen concentration C _b of the outside air and the thermal conductivity λ _b of the outside air may be unknown.

FIG. 10 schematically illustrates an example of an outline for measuring the thermal conductivity of the outside air and the oxygen concentration of the outside air in the above case. As shown in FIG. 10, a thermal conductivity measuring sensor 30 for measuring the thermal conductivity of the outside air and an oxygen concentration meter 31 for measuring the oxygen concentration of the outside air are provided separately from the oxygen concentration measuring device 1A. Then, the air existing in the installation environment of the oxygen concentrator, which is outside air, is allowed to flow into the thermal conductivity measurement sensor 30 without passing through the filter 3 of the oxygen concentration measurement device 1A. Then, the thermal conductivity λ _b of outside air is measured by the thermal conductivity measuring sensor 30 . Also, the oxygen concentration _Cb of the outside air flowing out from the thermal conductivity measurement sensor 30 is measured by the oxygen concentration meter 31 . Before measuring the mixed gas to be measured in this way, the oxygen concentration _Cb contained in the outside air and the thermal conductivity _λb of the outside air may be temporarily measured by means other than the oxygen concentration measuring device 1A. . Then, the measured oxygen concentration C _b and the thermal conductivity λ _b of the outside air are used when calculating the oxygen concentration contained in the mixed gas to be measured in the same manner as described above.

[Action/effect]
The oxygen concentration measuring device 1A as described above is used when the composition of the air itself existing in the installation environment changes due to a change in the installation environment of the oxygen concentrator, the ratio of the components of the outside air changes, or when the installation environment of the oxygen concentrator changes. Even if the physical properties of the air are unknown, the oxygen concentration C _b of the outside air and the thermal conductivity λ _b of the outside air measured by another measuring means can be obtained. Equation (1) can then be updated based on the obtained C _b and λ _b . Also, the oxygen concentration contained in the mixed gas can be calculated based on the updated formula (1). Also, the correspondence shown in FIG. 4 can be updated. That is, the oxygen concentration measuring device 1A can accurately measure the concentration of oxygen in the mixed gas to be measured regardless of changes in the installation environment of the oxygen concentrator.

<4.2>
Although the oxygen concentration measuring device 1 described above measures the oxygen concentration in air containing at least three components of oxygen, nitrogen, and argon, the measurement target is not limited to the oxygen concentration contained in air. For example, the oxygen concentration measuring device 1 according to the present embodiment may measure the concentration of any one of the components A, B and C in a mixed gas containing at least three components A, B and C. . Further, when the ratio of the component A and the component B contained in the mixed gas is substantially the same, the component A and the component B are regarded as one component, and the mixed gas is regarded as two components, and the concentration of the component AB or the component C is detected. You may In this case, the oxygen concentration measuring device 1B causes the mixed gas in which the component ratio of the component AB and the component C is changed to flow into the inside of the flow tube member 2 . Then, the output of the thermopile 7A corresponding to the component ratio is measured, and the correspondence relationship between the component ratio and the output of the thermopile 7A is stored. Then, the oxygen concentration measuring device 1B calculates the concentration of the component AB or the component C from the output value output from the thermopile 7A and the corresponding relationship when the mixed gas to be measured is flowed through the flow tube member. may

[Action/effect]
According to the oxygen concentration measuring device 1B as described above, when the ratio of the component A and the component B contained in the mixed gas is substantially the same, the concentration of the component AB or the component C can be calculated more easily.

<4.3>
The thermal conductivities of oxygen, nitrogen, and argon contained in the mixed gas measured by the oxygen concentration measuring device 1 are different. However, of the at least three components A, B, and C contained in the mixed gas, if the components A and B have substantially the same thermal conductivity and the components A and C have different thermal conductivities, the mixed gas is different. It can be assumed that the gas consists of two components of thermal conductivity. Therefore, the oxygen concentration measuring device 1</b>C causes the mixed gas in which the component ratio of the components A, B, and C is changed to flow into the inside of the flow tube member 2 . Then, the output of the thermopile 7A corresponding to the component ratio is measured, and the correspondence relationship between the component ratio and the output of the thermopile 7A is stored. Such an oxygen concentration measuring device 1C can calculate the concentration of the component C from the output value output from the thermopile 7A and the corresponding relationship when the mixed gas to be measured is flowed through the flow tube member. can.

[Action/effect]
According to the oxygen concentration measuring device 1C as described above, of the at least three components A, B, and C contained in the mixed gas, the components A and B have substantially the same thermal conductivity, and the heat If the conductivities are different, the concentration of component C can be measured more easily.

<4.4>
When the mixed gas measured by the above oxygen concentration measuring device 1 contains at least three components A, B, and C, the value obtained by multiplying the content of component C by the thermal conductivity of C is the total mixed gas If the thermal conductivity is extremely small with respect to , component C may be ignored and the mixed gas may be assumed to consist of two components, component A and component B. In other words, if the influence of change in component C is small, the mixed gas may be assumed to consist of component A and component B. In such a case, the oxygen concentration measuring device 1</b>D causes a mixed gas in which the component ratio of the component A and the component B is changed to flow into the flow tube member 2 . Then, the output of the thermopile 7A corresponding to the component ratio is measured, and the correspondence relationship between the component ratio and the output of the thermopile 7A is stored. Then, the oxygen concentration measuring device 1D calculates the concentration of the component A or the component B from the output value output from the thermopile 7A when the mixed gas to be measured is flowed through the flow tube member 2 and the corresponding relationship. You may

[Action/effect]
According to the oxygen concentration measuring device 1D as described above, the concentration of component A or component B of a mixed gas containing three types of components A, B, and C can be measured more easily when the influence of changes in component C is small. can do.

<4.5>
Further, in the oxygen concentration measuring device 1 described above, the first storage unit 13 stores the output of the thermopile 7A calculated by the control unit 10 and the constants a, b, and c of the equation (3) representing the thermal conductivity of the mixed gas. remembers the value. The second storage unit 14 stores the measured oxygen concentration C _a of the oxygen-enriched gas at the earliest stage and the thermal conductivity λ _a of the oxygen-enriched gas at the earliest stage. The second storage unit 14 also stores the oxygen concentration _Cb of the outside air and the thermal conductivity _λb of the outside air. However, the oxygen concentration measuring device 1E may store a numerical value for directly converting the electrical signal output from the thermopile 7A into the component ratio of the mixed gas.

[Action/effect]
With such an oxygen concentration measuring device 1E as well, the oxygen concentration contained in the mixed gas to be measured is calculated using the output from the thermopile 7A. Also, the amount of information stored in storage devices such as ROM and RAM is reduced. Therefore, the capacity of the storage device can be reduced.

Each of the embodiments disclosed above can be combined.

＜付記３＞
前記酸素濃度算出部（１０）は、前記濃縮ガスにおける、前記初期濃縮ガスと、前記酸素濃縮手段（３）を透過した空気との存在比率を変化させた場合の熱伝導率及び酸素濃度の値によって算出された、前記濃縮ガスにおける熱伝導率と酸素濃度との対応関係（図４）を参照して、前記濃縮ガスの酸素濃度を算出することを特徴とする、
付記１に記載の酸素濃度測定装置（１、１Ａ）。
＜付記４＞
前記対応関係（図４）は、前記濃縮ガスに含まれる前記酸素濃縮手段（３）を透過した空気の割合が増加することに従い、前記濃縮ガスの熱伝導率に対して前記濃縮ガスに含まれる酸素の濃度は単調に変化する関係を含む、
付記３に記載の酸素濃度測定装置（１、１Ａ）。
＜付記５＞
前記空気に含まれる酸素の濃度と、前記空気の熱伝導率と、を測定する測定手段（３０、３１）を更に備える、
付記１から４のうち何れか１項に記載の酸素濃度測定装置（１）。
＜付記６＞
酸素濃縮器において濃縮後の酸素の濃度を測定する酸素濃度測定方法であって、
空気に含まれる窒素を除去し、酸素を濃縮する酸素濃縮手段（３）によって酸素が濃縮された濃縮ガスの熱伝導率を算出する熱伝導率算出ステップ（Ｓ１０２）と、
前記濃縮ガスの熱伝導率に対する前記濃縮ガスに含まれる酸素の濃度を算出する酸素濃度算出ステップ（Ｓ１０３）と、を有し、
前記濃縮ガスは、前記酸素濃縮手段（３）の使用が開始された初期状態において、該酸素濃縮手段（３）によって酸素が濃縮された初期濃縮ガスと、該酸素濃縮手段（３）を透過した空気と、を含み、
前記酸素濃度算出ステップ（Ｓ１０３）においては、前記初期濃縮ガスにおける熱伝導率及び酸素濃度と、前記空気における熱伝導率及び酸素濃度と、に基づいて、前記濃縮ガスの熱伝導率に対する前記濃縮ガスに含まれる酸素の濃度を算出することを特徴とする、
酸素濃度測定方法。
＜付記７＞
前記酸素濃度算出ステップ（Ｓ１０３）においては、前記初期濃縮ガスにおける熱伝導率をλ_ａ、酸素濃度をＣ_ａとし、前記酸素濃縮手段（３）を透過した空気における熱伝導率をλ_ｂ、酸素濃度をＣ_ｂとし、前記熱伝導率算出ステップ（Ｓ１０２）において算出された前記濃縮ガスの熱伝導率をλ_ｘとし、前記濃縮ガスの酸素濃度をＣ_ｘとしたときに、数式（１）によりＣ_ｘを算出することを特徴とする、
付記６に記載の酸素濃度測定方法。

＜付記８＞
前記酸素濃度算出ステップ（Ｓ１０３）においては、前記濃縮ガスにおける、前記初期濃縮ガスと、前記酸素濃縮手段（３）を透過した空気との存在比率を変化させた場合の熱伝導率及び酸素濃度の値によって算出された、前記濃縮ガスにおける熱伝導率と酸素濃度との対応関係（図４）を参照して、前記濃縮ガスの酸素濃度を算出することを特徴とする、
付記６に記載の酸素濃度測定方法。 In order to allow comparison between the constituent elements of the present invention and the configurations of the embodiments, the constituent elements of the present invention will be described below with reference numerals in the drawings.
<Appendix 1>
An oxygen concentration measuring device (1, 1A) for measuring the concentration of oxygen after concentration in an oxygen concentrator,
a heating unit (6) for removing nitrogen contained in the air and heating the concentrated gas in which oxygen is concentrated by the oxygen concentrating means (3) for concentrating the oxygen;
Output units (7A, 7B) arranged side by side across the heating unit (6) and performing output based on the temperature of the concentrated gas;
a thermal conductivity calculation unit (10) for calculating the thermal conductivity of the concentrated gas from the outputs of the output units (7A, 7B);
an oxygen concentration calculation unit (10) for calculating the concentration of oxygen contained in the concentrated gas with respect to the thermal conductivity of the concentrated gas calculated by the thermal conductivity calculation unit (10);
The enriched gas passes through the initial enriched gas in which oxygen is enriched by the oxygen enrichment means (3) and the oxygen enrichment means (3) in the initial state when the use of the oxygen enrichment means (3) is started. including air and
The oxygen concentration calculation unit (10) calculates the thermal conductivity and oxygen concentration of the enriched gas for the thermal conductivity of the enriched gas based on the thermal conductivity and oxygen concentration of the initial enriched gas and the thermal conductivity and oxygen concentration of the air. characterized by calculating the concentration of oxygen contained,
Oxygen concentration measuring device (1, 1A).
<Appendix 2>
The oxygen concentration calculator (10) sets the thermal conductivity of the initially concentrated gas to λ _a , the oxygen concentration to C _a , the thermal conductivity of the air that has passed through the oxygen concentrating means (3) to λ _b , and the oxygen concentration to is C _b , the thermal conductivity of the concentrated gas calculated by the thermal conductivity calculation unit (10) is λ _x , and the oxygen concentration of the concentrated gas is C _x , then C characterized by calculating _x ,
The oxygen concentration measuring device (1, 1A) according to appendix 1.

<Appendix 3>
The oxygen concentration calculator (10) calculates the values of the thermal conductivity and the oxygen concentration when the abundance ratio of the initial enriched gas and the air that has passed through the oxygen enrichment means (3) in the enriched gas is changed. The oxygen concentration of the enriched gas is calculated by referring to the correspondence relationship between the thermal conductivity and the oxygen concentration in the enriched gas (FIG. 4) calculated by
The oxygen concentration measuring device (1, 1A) according to appendix 1.
<Appendix 4>
Said correspondence (FIG. 4) is contained in said enriched gas for the thermal conductivity of said enriched gas as the proportion of air permeated through said oxygen enrichment means (3) contained in said enriched gas increases. The concentration of oxygen contains a monotonically changing relationship,
The oxygen concentration measuring device (1, 1A) according to appendix 3.
<Appendix 5>
Further comprising measuring means (30, 31) for measuring the concentration of oxygen contained in the air and the thermal conductivity of the air,
The oxygen concentration measuring device (1) according to any one of Appendices 1 to 4.
<Appendix 6>
An oxygen concentration measuring method for measuring the concentration of oxygen after concentration in an oxygen concentrator,
a thermal conductivity calculation step (S102) of calculating the thermal conductivity of the concentrated gas in which oxygen is concentrated by the oxygen concentrating means (3) for removing nitrogen contained in the air and concentrating the oxygen;
an oxygen concentration calculation step (S103) for calculating the concentration of oxygen contained in the enriched gas with respect to the thermal conductivity of the enriched gas;
The enriched gas passes through the initial enriched gas in which oxygen is enriched by the oxygen enrichment means (3) and the oxygen enrichment means (3) in the initial state when the use of the oxygen enrichment means (3) is started. including air and
In the oxygen concentration calculation step (S103), based on the thermal conductivity and oxygen concentration in the initial enriched gas and the thermal conductivity and oxygen concentration in the air, the thermal conductivity of the enriched gas with respect to the thermal conductivity of the enriched gas characterized by calculating the concentration of oxygen contained in
Oxygen concentration measurement method.
<Appendix 7>
In the oxygen concentration calculating step (S103), λ a is the thermal conductivity of the initially concentrated gas, _Ca is the oxygen concentration, λ _b is the thermal conductivity of the air that has passed through the oxygen concentrating means (3 ₎ , oxygen Let C _b be the concentration, let λ _x be the thermal conductivity of the enriched gas calculated in the thermal conductivity calculation step (S102), and let C _x be the oxygen concentration of the enriched gas. C _x is calculated,
The oxygen concentration measuring method according to appendix 6.

<Appendix 8>
In the oxygen concentration calculation step (S103), the thermal conductivity and the oxygen concentration when changing the abundance ratio of the initial enriched gas and the air that has passed through the oxygen enrichment means (3) in the enriched gas. The oxygen concentration of the enriched gas is calculated by referring to the correspondence relationship between the thermal conductivity and the oxygen concentration in the enriched gas (FIG. 4) calculated by the value,
The oxygen concentration measuring method according to appendix 6.

1, 1A, 1B, 1C, 1D, 1E: Oxygen concentration measuring device 2, 2A: Flow tube member 3: Filter 4: Substrate 5: Thin film 6: Heaters 7A, 7B: Thermopile 8: Contact 9: Contact 10: Control unit 11: Measurement unit 12: Sensor unit 13: First storage unit 14: Second storage unit 15: Input unit 16: Output unit 20: Cavity 30: Thermal conductivity measurement sensor 31: Oxygen concentration meter

Claims (8)

An oxygen concentration measuring device for measuring the concentration of oxygen after concentration in an oxygen concentrator,
a heating unit that removes nitrogen contained in the air and heats the concentrated gas in which oxygen is concentrated by the oxygen concentrating means that concentrates the oxygen;
an output unit that is arranged side by side across the heating unit and performs output based on the temperature of the concentrated gas;
a thermal conductivity calculation unit that calculates the thermal conductivity of the concentrated gas from the output of the output unit;
an oxygen concentration calculation unit that calculates the concentration of oxygen contained in the concentrated gas with respect to the thermal conductivity of the concentrated gas calculated by the thermal conductivity calculation unit;
The enriched gas includes an initial enriched gas in which oxygen is enriched by the oxygen enrichment means in an initial state when the use of the oxygen enrichment means is started, and air that has passed through the oxygen enrichment means,
The oxygen concentration calculation unit calculates the oxygen contained in the enriched gas with respect to the thermal conductivity of the enriched gas based on the thermal conductivity and oxygen concentration of the initial enriched gas and the thermal conductivity and oxygen concentration of the air. characterized by calculating the concentration of
Oxygen concentration measuring device. The oxygen concentration calculation unit sets λ _{a as the thermal conductivity and C a as the oxygen concentration in the initially concentrated gas, λ b as the thermal conductivity, and C b as the} oxygen concentration in the air that has passed through the oxygen concentrating means. When the thermal conductivity of the enriched gas calculated by the thermal conductivity calculator is _λx , and the oxygen concentration of the enriched gas is _Cx , _Cx is calculated by Equation (1). ,
The oxygen concentration measuring device according to claim 1.

The oxygen concentration calculation unit calculates the values of the thermal conductivity and the oxygen concentration when changing the abundance ratio of the initial enriched gas and the air that has passed through the oxygen enrichment means in the enriched gas, By referring to the correspondence relationship between the thermal conductivity and the oxygen concentration in the enriched gas, the oxygen concentration of the enriched gas is calculated,
The oxygen concentration measuring device according to claim 1. According to the corresponding relationship, the concentration of oxygen contained in the enriched gas changes monotonously with respect to the thermal conductivity of the enriched gas as the proportion of air that has permeated through the oxygen enrichment means contained in the enriched gas increases. including relationships that
The oxygen concentration measuring device according to claim 3. Further comprising measuring means for measuring the concentration of oxygen contained in the air and the thermal conductivity of the air,
The oxygen concentration measuring device according to any one of claims 1 to 4. An oxygen concentration measuring method for measuring the concentration of oxygen after concentration in an oxygen concentrator,
a thermal conductivity calculation step of calculating the thermal conductivity of a concentrated gas in which oxygen is concentrated by an oxygen concentrating means for removing nitrogen contained in air and concentrating oxygen;
an oxygen concentration calculation step of calculating the concentration of oxygen contained in the enriched gas with respect to the thermal conductivity of the enriched gas;
The enriched gas includes an initial enriched gas in which oxygen is enriched by the oxygen enrichment means in an initial state when the use of the oxygen enrichment means is started, and air that has passed through the oxygen enrichment means,
In the oxygen concentration calculating step, based on the thermal conductivity and oxygen concentration in the initial enriched gas and the thermal conductivity and oxygen concentration in the air, characterized by calculating the concentration of oxygen,
Oxygen concentration measurement method. In the oxygen concentration calculating step, λ _a is the thermal conductivity of the initially concentrated gas, _{Ca is the oxygen concentration, λ b is} the thermal conductivity of the air that has passed through the oxygen concentrating means, and C _b is the oxygen concentration; When the thermal conductivity of the concentrated gas calculated in the thermal conductivity calculation step is _λx and the oxygen concentration of the concentrated gas is _Cx , _Cx is calculated by Equation (1). do,
The oxygen concentration measuring method according to claim 6.

In the oxygen concentration calculating step, the values of the thermal conductivity and the oxygen concentration when changing the existence ratio of the initial enriched gas and the air that has passed through the oxygen concentrating means in the enriched gas are calculated. By referring to the correspondence relationship between the thermal conductivity and the oxygen concentration in the enriched gas, the oxygen concentration of the enriched gas is calculated,
The oxygen concentration measuring method according to claim 6.

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