Oxygen concentration device

Abstract

The abnormality of a flow path switching valve on the upstream side of an oxygen concentration device is detected on the basis of the waveform of a pressure sensor provided in a product tank. An oxygen concentration device is provided with a monitoring means for monitoring the state of a flow path switching means on the basis of the output of a pressure sensor of a product tank, and is characterized by detecting an abnormality in a flow path switching valve when the value detected by the pressure sensor in an adsorption step and / or a desorption step deviates from a prescribed threshold range.

Description

Technical Field

[0001] The present invention relates to a pressure swing adsorption type oxygen concentrator for separating oxygen from air. Background Art

[0002] The number of patients suffering from respiratory diseases such as asthma, emphysema, chronic bronchitis, and viral pneumonia caused by the recent novel coronavirus infection has increased, and one of the most effective treatments is oxygen inhalation therapy. Such oxygen inhalation therapy refers to a therapy in which patients with respiratory diseases inhale oxygen or oxygen-concentrated gas. As the supply source of oxygen used therein, oxygen concentrators, liquid oxygen, oxygen cylinders, etc. are known, but oxygen concentrators are the mainstream in home oxygen therapy for reasons such as the simplicity of use and the ease of maintenance and management.

[0003] An oxygen concentrator is a device that separates and concentrates about 21% of oxygen present in the air and supplies it. As such devices, there are known membrane oxygen concentrators that use a membrane that selectively allows oxygen to permeate, and pressure swing adsorption oxygen concentrators that use an adsorbent that can preferentially adsorb nitrogen or oxygen. However, since a high concentration of oxygen of more than 90% can be obtained, pressure swing adsorption oxygen concentrators are mainly used as devices for home oxygen therapy.

[0004] The pressure swing adsorption type oxygen concentrator is capable of continuously generating a high-concentration oxygen-enriched gas by alternately and repeatedly performing the following steps: a pressurization / adsorption step, in which air compressed by a compressor is supplied to an adsorption cylinder filled with molecular sieve zeolite of type 5A, type 13X, type Li-X, etc., which is an adsorbent that selectively adsorbs nitrogen as compared to oxygen, so that the adsorbent adsorbs nitrogen under pressurized conditions to obtain unadsorbed oxygen; and a decompression / desorption step, in which the pressure in the aforementioned adsorption cylinder is reduced to atmospheric pressure or below, and the adsorbent is regenerated by purging the nitrogen adsorbed on the adsorbent.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2018-175542 Summary of the invention

[0008] Problems to be solved by the invention

[0009] In an oxygen concentrator that uses a compressor as a supply source of pressurized air, a pressure sensor is installed on the discharge side of the compressor to detect the adsorption pressure, and a safety mechanism is provided to detect pressure abnormalities associated with compressor abnormalities and issue an alarm, reduce the speed of the compressor, or stop it. In addition, a relief valve is also provided to ensure the safety of the equipment.

[0010] Furthermore, as described in Patent Document 1, there is also known an oxygen concentrator having a function of detecting abnormality of an intake valve or an exhaust valve based on a detection result of a compressor pressure.

[0011] Since the raw air contains a lot of water vapor, the downstream side of the compressor becomes a high humidity environment under pressurized conditions. Therefore, there is a problem of condensation in the pipe connected to the pressure sensor. As a solution, it is necessary to set a dehumidification function for the raw air or use an expensive condensation prevention pipe in the connecting pipe. In contrast, the downstream side of the adsorption cylinder of the oxygen concentrator is dehumidified by the adsorption material to become a dry oxygen environment, so by detecting the pressure in the product tank, such dehumidification-related equipment is no longer required.

[0012] On the other hand, since the pressure of the product tank fluctuates depending on the oxygen generation conditions and the period of the adsorption and desorption processes, it is difficult to detect which of the components on the upstream side of the product tank, such as the compressor, adsorption cylinder, flow path switching valve, etc., which are believed to be the cause of the pressure abnormality, has caused the abnormality based on the fluctuation of the product tank pressure.

[0013] Furthermore, in the oxygen concentrator, since the oxygen generation amount is adjusted according to the oxygen supply amount, even in normal times, the values ​​of the adsorption pressure and the product tank pressure vary greatly in association with the control of the compressor rotation speed.

[0014] Means used to solve problems

[0015] The present inventors have found a method for detecting an abnormal portion of a flow path switching valve on the upstream side based on the waveform of a pressure sensor provided on a product tank.

[0016] The present invention provides the following oxygen concentrator.

[0017] 1. An oxygen concentrator, which is a pressure swing adsorption type oxygen concentrator, comprises: a plurality of adsorption cylinders filled with an adsorbent that selectively adsorbs nitrogen over oxygen under pressurized conditions; a compressor that supplies pressurized air to the adsorption cylinders; a flow path switching valve that comprises a supply valve that supplies pressurized air to each adsorption cylinder and an exhaust valve that discharges exhaust gas from the adsorption cylinder to the outside of the system; a product tank that temporarily stores oxygen generated from the adsorption cylinder; and a pressure sensor that detects product tank pressure; oxygen is continuously generated by sequentially switching and repeatedly performing an adsorption process for generating oxygen under a pressurized state and a desorption process for discharging nitrogen under a reduced pressure state for each adsorption cylinder; characterized in that a monitoring mechanism is provided for monitoring the state of the flow path switching mechanism based on the output of the pressure sensor, and when the detection value of the pressure sensor in the adsorption process and / or the desorption process deviates from a range of a specified threshold value, that is, when it deviates from a specified range on the positive side or the negative side, an abnormality of the flow path switching valve is detected.

[0018] 2. In the oxygen concentrator as described in 1 above, when the difference or ratio of the product tank pressures at specific timings of the adsorption process or desorption process of the plurality of adsorption cartridges is greater than a predetermined threshold, the monitoring means determines that the flow path switching valve is abnormal.

[0019] 3. In the oxygen concentrator according to 2 above, the specific timing is a predetermined time before the end of the adsorption step or the desorption step.

[0020] 4. In the oxygen concentrator as described in 1 above, when the product tank pressure at the end of the adsorption process in one of the multiple adsorption cylinders is greater than a specified threshold value relative to the product tank pressure at the beginning, and the product tank pressure at the end of the desorption process is greater than a specified threshold value relative to the product tank pressure at the beginning, the above-mentioned monitoring mechanism determines that there is an abnormality in the supply valve that supplies pressurized air to the adsorption cylinder.

[0021] 5. In the oxygen concentrator as described in 1 above, when the product tank pressure at the end of the desorption process in one of the multiple adsorption cylinders is lower than a specified threshold value relative to the product tank pressure at the beginning, and when the product tank pressure at the end of the adsorption process is higher than a specified threshold value relative to the product tank pressure at the beginning, the monitoring mechanism determines that there is an abnormality in the exhaust valve that discharges the exhaust gas from the adsorption cylinder to the outside of the system.

[0022] 6. In the oxygen concentrator as described in 1 above, when the difference or ratio between the maximum pressure and the minimum pressure of the product tank in the adsorption process or the desorption process of each adsorption cylinder is greater than a predetermined threshold, the monitoring means determines that the flow path switching valve is abnormal.

[0023] 7. In the oxygen concentrator as described in 1 above, when the difference or ratio between the maximum pressures of the product tanks in the adsorption process and the desorption process of each adsorption cylinder is greater than a predetermined threshold value, the monitoring means determines that the flow path switching valve is abnormal.

[0024] 8. The oxygen concentrator according to any one of 1 to 7 above, wherein the predetermined threshold value is a value determined based on a product tank pressure set according to oxygen supply conditions of the oxygen concentrator.

[0025] 9. In the oxygen concentrator as described in 8 above, the oxygen supply condition is a set flow rate of the oxygen concentrator, an oxygen supply mode under a continuous flow or a breathing synchronized flow, an adsorption cylinder pressure or a rotation speed of a compressor.

[0026] Effects of the Invention

[0027] In the oxygen concentrator of the present invention, the pressure sensor for detecting the adsorption pressure can be installed not on the discharge side of the compressor containing a large amount of water vapor, but on the product tank storing the oxygen concentrated gas in a dry state. As a result, it is possible to detect abnormalities in the equipment on the upstream side of the product tank, and it is possible to detect abnormalities in the flow path switching valves such as the supply valve and the exhaust valve based on the relationship between the change in the pressure waveform of the product tank and the switching timing of the adsorption and desorption process. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A diagram showing the structure of the oxygen concentrator of the present invention.

[0029] Figure 2 FIG. 1 shows the fluctuation of the product tank pressure of the oxygen concentrator of the present invention.

[0030] Figure 3 FIG. 1 shows the fluctuation of the product tank pressure when an abnormality occurs in the supply valve of the oxygen concentrator of the present invention.

[0031] Figure 4 FIG. 1 shows the fluctuation of the product tank pressure when an exhaust valve of the oxygen concentrator of the present invention is abnormal. DETAILED DESCRIPTION

[0032] Embodiments of the oxygen concentrator according to the present invention will be described with reference to the drawings.

[0033] Figure 1 This is a schematic diagram of a pressure swing adsorption type oxygen concentrator as an embodiment of the present invention. The pressure swing adsorption type oxygen concentrator of the present invention comprises a compressor 101 for supplying raw air, an adsorption cartridge 102 filled with an adsorbent that selectively adsorbs nitrogen over oxygen, a supply valve 103 as a flow path switching mechanism for switching the adsorption and desorption process, an exhaust valve 104, and a pressure equalizing valve 105. The oxygen-enriched gas separated from the raw air is adjusted to a predetermined flow rate by a pressure regulating valve 108 and a control valve 109 as flow rate setters, and then humidified by a water humidifier 110 and supplied to the user by a cannula 111.

[0034] Ordinary air contains about 21% oxygen, about 77% nitrogen, 0.8% argon, and 1.2% of gases other than carbon dioxide. In such a device, the required oxygen is separated and taken out as breathing gas. In the adsorption process, the adsorption cylinder filled with an adsorbent composed of zeolite or the like that selectively adsorbs nitrogen molecules compared to oxygen molecules is switched to the adsorption cylinder 102 to which the raw air is supplied by controlling the opening and closing of the supply valve 103 and the exhaust valve 104, and pressurized air is sequentially supplied from the compressor 101. In the pressurized adsorption cylinder, about 77% of the nitrogen contained in the raw air is selectively adsorbed and removed, thereby separating the oxygen-enriched gas.

[0035] The above-mentioned adsorption cylinder is composed of a cylindrical container filled with an adsorption material that selectively adsorbs nitrogen over oxygen. The number of adsorption cylinders is determined by the relationship with the amount of oxygen generated. In order to continuously and efficiently produce oxygen-enriched gas from raw air, it is preferred to use Figure 1 The double-cylinder and multi-cylinder adsorption cylinders shown.

[0036] The oxygen-enriched gas mainly composed of oxygen not adsorbed by the adsorption cylinder flows into the product tank 107 through the check valve 106 provided to prevent the gas from flowing back to the adsorption cylinder, and is temporarily stored.

[0037] In order to continuously generate oxygen-enriched gas, it is necessary to desorb and remove the nitrogen adsorbed on the adsorbent filled in the adsorption cylinder. Therefore, in the desorption process, the adsorption cylinder is connected to the exhaust line by closing the supply valve and opening the exhaust valve, and the adsorption cylinder in the pressurized state is switched to the atmosphere open state, so that the nitrogen adsorbed in the pressurized state is desorbed and the adsorbent is regenerated.

[0038] In the two adsorption columns, the operations are controlled by staggering the steps. When oxygen is generated while performing the adsorption step in one adsorption column, the adsorbent is regenerated by performing the desorption step in the other adsorption column. Oxygen is continuously generated by switching the steps.

[0039] Unadsorbed oxygen is continuously generated by repeating the following steps alternately: adsorption step, supplying pressurized air from the compressor 101 to the adsorption cylinder 102 (a) via the supply valve 103 (a), adsorbing nitrogen to generate oxygen; desorption step, depressurizing the other adsorption cylinder 102 (b), desorbing the adsorbed nitrogen, and exhausting it to the outside of the system via the exhaust valve 104 (b). During this period, the adsorption and desorption steps are repeated while the following steps are incorporated to generate oxygen-enriched gas: pressure equalization step, equalizing the pressure between the adsorption cylinders via the pressure equalization valve; purge step, pressurizing the adsorption cylinders, generating oxygen while allowing a portion of it to flow to the other adsorption cylinder, thereby improving the regeneration efficiency.

[0040] Oxygen-concentrated gas is produced from raw air and temporarily stored in a product tank. The oxygen-concentrated gas stored in the product tank contains high-concentration oxygen-concentrated gas such as 95%, and its supply flow rate and pressure are controlled by a flow setter such as a pressure regulating valve or a control valve and supplied to a humidifier, and the humidified oxygen-concentrated gas is supplied to the patient. In such a humidifier, a bubbling humidifier or a surface evaporation humidifier using water as a humidification source can be used.

[0041] An ultrasonic oxygen concentration / flow sensor can also be used to detect the flow rate and oxygen concentration of the oxygen concentrated gas supplied to the user, and feedback control can be performed on the compressor speed and the opening and closing time of the flow switching valve based on the oxygen concentration detection value and the oxygen supply flow value to control oxygen generation.

[0042] Since the molecular sieve zeolite of Na-X type, Li-X type, MD-X type, etc., which is an adsorbent that selectively adsorbs nitrogen over oxygen filled in the adsorption cylinder, also adsorbs moisture in the air while adsorbing nitrogen, the generated oxygen-concentrated gas is separated as a gas in a substantially absolutely dry state. In order to prevent the nostrils and the like from drying out due to continuous inhalation of such oxygen-concentrated gas, a water humidifier that humidifies the oxygen-concentrated gas by bubbling in humidified water or a water-free humidifier using a hollow fiber membrane that selectively transmits water vapor in the air may be provided as needed in the middle of the pipe connecting the product tank that once stores the generated oxygen-concentrated gas and the cannula that supplies oxygen to the patient.

[0043] exist Figure 2 1 shows the pressure waveform of the pressure sensor 112 installed in the product tank 107. In order to achieve energy saving, the compressor pressure as the adsorption pressure and the order of the adsorption and desorption processes are controlled so that the oxygen generation amount and the oxygen supply amount become constant. The product tank pressure can see a slight pressure drop in the pressure equalization process when switching between the adsorption and desorption processes. The steady-state pressure varies depending on the supply flow rate, but the product tank pressure is maintained at a roughly constant value.

[0044] exist Figure 3 : The pressure waveform of the product tank is shown in the case where an abnormality occurs in the supply valve and one of the supply valves is not opened. The solenoid valve used in the supply valve, exhaust valve, etc. is used to close the supply path to the adsorption cylinder when stopped to prevent moisture deterioration of the adsorbent. It is an open state when the power is turned on and a closed state when the power is turned off. Although there are many abnormal situations where the solenoid valve does not open even if a voltage is applied, there are also opposite situations.

[0045] When one supply valve is not opened, oxygen generation in the adsorption process cannot be achieved, so the product tank pressure in this process decreases. When switching to the desorption process, the supply valve that supplies pressurized air to the other adsorption cylinder works normally to generate oxygen, so the product tank pressure is restored. By detecting such adsorption and desorption processes and changes in product tank pressure, it is possible to detect abnormalities in the supply valve.

[0046] exist Figure 4In the figure, the pressure waveform of the product tank is shown when an abnormality occurs in the exhaust valve and one exhaust valve becomes closed. When the exhaust valve fails and becomes always closed, the desorbed nitrogen and the purge gas can no longer be discharged in the desorption process of the corresponding adsorption cylinder. Since the amount of oxygen generated in the adsorption process of the adsorption cylinder on the opposite side that is purged and discharged is generated more, the product tank pressure gradually rises. Even if the adsorption and desorption process is switched, the adsorption cylinder on the adsorption process side with the abnormal exhaust valve maintains a high pressure. Pressurized air is supplied to such an adsorption cylinder, and the product tank pressure further rises. And since the amount of generated gas and the amount of supplied gas are balanced with the start of the purge and exhaust process, it becomes a constant pressure. On the other hand, in the adsorption cylinder with a normal exhaust valve, the adsorption cylinder pressure drops significantly due to the pressure equalization between the adsorption cylinders at the beginning of the adsorption process, and the product tank pressure also drops accordingly, but then the pattern of rising, constant pressure maintenance, and falling is repeated with the adsorption and desorption process.

[0047] Thus, it is not possible to determine abnormality of a flow path switching mechanism such as a supply valve or an exhaust valve simply by the magnitude of the product tank pressure.

[0048] In the pressure swing adsorption type oxygen concentrator of the present invention, it is characterized in that it has a monitoring mechanism that monitors the state of the flow switching mechanism based on the output of the pressure sensor of the product tank, and by simultaneously monitoring the stages of the adsorption process and / or desorption process accompanied by the switching of the flow switching mechanism and the product tank pressure, when the detection value of the pressure sensor is greater than a specified threshold value, that is, when it deviates from the specified range on the positive side or the negative side, an abnormality of the flow switching valve is detected.

[0049] Such a predetermined threshold value is a value determined based on the product tank pressure, which is set according to a set flow rate, a supply mode such as continuous supply, and a breathing synchronized supply as an oxygen supply condition of the oxygen concentrator, and the rotation speed of the compressor associated therewith.

[0050] The adsorption process of multiple adsorption cylinders, that is, the product tank pressure at a specific time of the adsorption process of the adsorption cylinder (a) and the product tank pressure at the same time of the adsorption process of the subsequent adsorption cylinder (b) originally represent the same pressure value ( Figure 3 3a, 3c), but when the difference or ratio between the two is greater than a predetermined threshold, the monitoring means determines that the flow path switching valve is abnormal. Such a specific timing is preferably determined by a predetermined time before the end of the adsorption process or desorption process, such as 10 seconds or 5 seconds before the end of the adsorption process or desorption process when the product tank pressure value is stable.

[0051] In addition, when the difference between the maximum pressure and the minimum pressure of the product tank in the adsorption process or the desorption process of each adsorption cylinder or the ratio of the two is greater than a specified threshold value determined by the differential pressure in normal times, or when the difference between the maximum pressure of the product tank in the adsorption process and the desorption process of each adsorption cylinder or the ratio of the two is greater than a specified threshold value, the monitoring mechanism can determine that the flow path switching valve is abnormal.

[0052] In addition, such a method can determine that the abnormality of the flow path switching valve has occurred, but cannot identify the abnormal location.

[0053] In the oxygen concentrator of the present invention, the monitoring means of the flow path switching means monitors the order of the adsorption and desorption steps and the pressure of the product tank. Figure 3 When the product tank pressure waveform indicates that the product tank pressure (3f) at the end of the adsorption process of the adsorption cylinder 102 (a) is greater than a specified threshold value (the differential pressure between 3b and 3c) relative to the product tank pressure (3e) at the beginning, and the product tank pressure (3e) at the end of the desorption process is greater than a specified threshold value relative to the product tank pressure (3d) at the beginning, the monitoring mechanism can determine that there is an abnormality in the supply valve 103 (a) that supplies pressurized air to the adsorption cylinder 102 (a).

[0054] In addition, in Figure 4 When the product tank pressure waveform indicates that the product tank pressure (4e) at the end of the desorption process of the adsorption cylinder 102 (a) is within a specified threshold relative to the product tank pressure (4d) at the beginning, and the product tank pressure (4f) at the end of the adsorption process is greater than the specified threshold relative to the product tank pressure (4e) at the beginning, the above-mentioned monitoring mechanism can determine that there is an abnormality in the exhaust valve 104 (a) that releases the exhaust gas from the adsorption cylinder to the outside of the system.

[0055] Industrial Applicability

[0056] The oxygen concentrator of the present invention can be used as a medical device with ensured safety suitable for home oxygen inhalation therapy for supplying oxygen to patients with chronic respiratory diseases and the like.

[0057] Description of Reference Numerals

[0058] 101 Compressor

[0059] 102 adsorption cylinder

[0060] 103 Supply valve

[0061] 104 Exhaust valve

[0062] 105 pressure equalizing valve

[0063] 106 Check Valve

[0064] 107 Product Cans

[0065] 108 pressure regulating valve

[0066] 109 control valve

[0067] 110 water humidifier

[0068] 111 Intubation

[0069] 112 Pressure Sensor

Claims

1. An oxygen concentrator, which is a pressure swing adsorption type oxygen concentrator, have: a plurality of adsorption cartridges filled with an adsorbent that selectively adsorbs nitrogen over oxygen under pressurized conditions; A compressor supplies pressurized air to the adsorption cylinder; A flow path switching valve, comprising a supply valve for supplying pressurized air to each adsorption cylinder and an exhaust valve for discharging exhaust gas from the adsorption cylinder to the outside of the system; A product tank temporarily stores oxygen generated from the adsorption cartridge; and Pressure sensor, detecting the pressure of the product tank; Oxygen is continuously generated by sequentially switching and repeating the adsorption process of generating oxygen in a pressurized state and the desorption process of discharging nitrogen in a depressurized state in each adsorption cylinder; It is characterized in that A monitoring means is provided for monitoring the state of the flow path switching means based on the output of the pressure sensor, and when the detection value of the pressure sensor in the adsorption process and / or the desorption process deviates from a predetermined threshold value range, abnormality of the flow path switching valve is detected.

2. The oxygen concentrator according to claim 1, characterized in that When the difference or ratio of the product tank pressures at specific timings of the adsorption process or the desorption process of the plurality of adsorption cylinders is greater than a predetermined threshold value, the monitoring means determines that the flow path switching valve is abnormal.

3. The oxygen concentrator according to claim 2, characterized in that The specific timing is a predetermined time before the end of the adsorption process or the desorption process.

4. The oxygen concentrator according to claim 1, characterized in that When the product tank pressure at the end of the adsorption process in one of the multiple adsorption cylinders is lower than a specified threshold value relative to the product tank pressure at the beginning, and the product tank pressure at the end of the desorption process is higher than the specified threshold value relative to the product tank pressure at the beginning, the monitoring mechanism determines that there is an abnormality in the supply valve that supplies pressurized air to the adsorption cylinder.

5. The oxygen concentrator according to claim 1, characterized in that: When the product tank pressure at the end of the desorption process in one of the multiple adsorption cylinders is greater than a specified threshold value relative to the product tank pressure at the beginning, and when the product tank pressure at the end of the adsorption process is greater than a specified threshold value relative to the product tank pressure at the beginning, the above-mentioned monitoring mechanism determines that there is an abnormality in the exhaust valve that releases the exhaust gas from the adsorption cylinder to the outside of the system.

6. The oxygen concentrator according to claim 1, characterized in that: When the difference or ratio between the maximum pressure and the minimum pressure of the product tank in the adsorption process or the desorption process of the plurality of adsorption cylinders is greater than a predetermined threshold value, the monitoring means determines that the flow path switching valve is abnormal.

7. The oxygen concentrator according to claim 1, characterized in that: When the difference or ratio of the maximum pressures of the product tanks in the adsorption process and the desorption process of the plurality of adsorption cylinders is greater than a predetermined threshold value, the monitoring means determines that the flow path switching valve is abnormal.

8. The oxygen concentrator according to any one of claims 1 to 7, wherein: The predetermined threshold value is a value determined based on the product tank pressure set according to the oxygen supply condition of the oxygen concentrator.

9. The oxygen concentrator according to claim 8, characterized in that The oxygen supply conditions are a set flow rate of the oxygen concentrator, an oxygen supply mode under a continuous flow or a breathing synchronized flow, an adsorption cartridge pressure, or a rotation speed of a compressor.

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