Oxygen concentrator

Abstract

To suppress reduction of the generation amount of an oxygen concentrated gas.SOLUTION: An oxygen concentrator 1 comprises: a compressor 5 for absorbing a gas and applying pressure; an electromagnetic valve V1 which serves as a switching part for switching the supply destination of the pressurized gas; a first absorption part 8A and a second absorption part 8B that receive the supply of the pressurized gas by the electromagnetic valve V1 from one end side and absorb nitrogen and moisture from the pressurized gas; a check valve 17A and a check valve 17B; a feedback line L9; a controller 13 that controls the electromagnetic valve V1, supplies the pressurized gas to one of the first absorption part 8A and the second absorption part 8B, and supplies an oxygen concentrated gas discharged from the absorption part to the other via the feedback line L9; an orifice OR1 as a first flow rate adjusting part provided on the feedback line L9; and an orifice OR2 as a second flow rate adjusting part provided on the secondary side of the check valve 17A and the check valve 17B.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an oxygen concentrator. [Background technology]

[0002] For example, concentrated oxygen is produced by separating nitrogen and moisture from air using an adsorbent such as zeolite by the PSA method or the like (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 6-246001 Summary of the Invention [Problem to be solved by the invention]

[0004] In oxygen concentrators, backflow may occur at the check valve due to fluctuations in pressure during the process of generating oxygen-enriched gas. When backflow occurs, the amount of oxygen-enriched gas output (production amount) may decrease.

[0005] In view of the above problems, an object of the present invention is to provide an oxygen concentrator that can suppress a decrease in the amount of oxygen-enriched gas produced. [Means for solving the problem]

[0006] In order to solve the above problems, an oxygen concentrator according to a first aspect of the present invention includes a first line, a compressor that draws in gas through the first line and pressurizes it, a switching unit that is supplied with pressurized gas discharged from the compressor and switches the supply destination of the pressurized gas, a first adsorption unit that is supplied with the pressurized gas from one end side by the switching unit and adsorbs nitrogen and moisture from the pressurized gas, a second adsorption unit that is supplied with the pressurized gas from one end side by the switching unit and adsorbs nitrogen and moisture from the pressurized gas, a first check valve that is provided at the other end side of the first adsorption unit and has the first adsorption unit side as its primary side, and a check valve in the second adsorption unit. the control unit is provided with a second check valve provided on the other end side with the second adsorption unit side as the primary side; a feedback line connecting the first adsorption unit and the first check valve and the second adsorption unit and the second check valve; a control device that controls the switching unit to supply the pressurized gas to either the first adsorption unit or the second adsorption unit and supply the oxygen-enriched gas discharged from the adsorption unit to the other of the first adsorption unit or the second adsorption unit via the feedback line; a first flow rate adjustment unit provided on the feedback line; and a second flow rate adjustment unit provided on the secondary side of the first check valve and the second check valve.

[0007] In the oxygen concentrator according to the second aspect of the present invention, each of the first flow rate adjustment unit and the second flow rate adjustment unit is an orifice.

[0008] In the oxygen concentrator according to the third aspect of the present invention, the orifice diameter of the second flow rate adjusting section is equal to or larger than the orifice diameter of the first flow rate adjusting section.

[0009] In the oxygen concentrator according to the fourth aspect of the present invention, the ratio of the orifice diameter of the second flow rate adjusting unit to the orifice diameter of the first flow rate adjusting unit is greater than 1 and less than 2.

[0010] In addition, in the oxygen concentrator according to the fifth aspect of the present invention, the secondary lines of the first check valve and the second check valve are connected to an air chamber, and the second flow rate adjustment unit is provided between the first check valve, the second check valve and the air chamber.

[0011] In addition, in the oxygen concentrator according to the sixth aspect of the present invention, the second flow rate adjustment unit is provided between the first check valve and the second check valve and the air chamber, and at a position closer to the first check valve and the second check valve than to the air chamber.

[0012] In addition, in an oxygen concentrator according to a seventh aspect of the present invention, the line is connected to the air chamber by joining the secondary side of the first check valve and the secondary side of the second check valve at a joining point, and the second flow rate adjustment unit is provided between the secondary side of the first check valve and the secondary side of the second check valve and the joining point, on each of the secondary side of the first check valve and the secondary side of the second check valve.

[0013] In the oxygen concentrator according to an eighth aspect of the present invention, the second flow rate adjusting unit is connected to each of the first check valve and the second check valve.

[0014] In addition, in the oxygen concentrator according to the ninth aspect of the present invention, the second flow rate adjustment unit is provided between the first check valve and the second check valve and the air chamber, and at a position closer to the air chamber than the first check valve and the second check valve.

[0015] In addition, in an oxygen concentrator according to a tenth aspect of the present invention, the line is connected to the air chamber by joining the secondary side of the first check valve and the secondary side of the second check valve at a confluence point, and the second flow rate adjustment unit is provided between the air chamber and the confluence point.

[0016] In addition, in the oxygen concentrator according to an eleventh aspect of the present invention, the second flow rate adjustment unit is provided between the air chamber and the confluence, and at a position closer to the air chamber than the confluence.

[0017] In the oxygen concentrator according to a twelfth aspect of the present invention, the second flow rate regulator is connected to the air chamber.

[0018] In addition, in an oxygen concentrator according to a thirteenth aspect of the present invention, the line is connected to the air chamber by joining the secondary side of the first check valve and the secondary side of the second check valve at a confluence point, and the second flow rate adjustment unit is provided between the confluence point and the air chamber and at a position closer to the confluence point than the air chamber.

[0019] In the oxygen concentrator according to a fourteenth aspect of the present invention, the second flow rate adjuster is connected to a confluence member that constitutes the confluence point. [Effects of the Invention]

[0020] According to the oxygen concentrator of the present invention, it is possible to suppress a decrease in the amount of oxygen-enriched gas produced. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a diagram illustrating an example of the overall configuration of an oxygen concentrator according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing an example of a comparison of the orifice diameters of the orifice OR1 and the orifice OR2 in FIG. [Figure 3] 1. FIG. 4 is a diagram showing an example of the relationship between the oxygen concentration and flow rate of the oxygen-enriched gas depending on the position of the orifice OR2 in FIG. [Figure 4] 2 is a timing chart showing an example of a processing flow of the oxygen concentrator of FIG. 1. [Figure 5] FIG. 10 is a diagram showing an example of the state of the oxygen concentrator during a period T2. [Figure 6]FIG. 10 is a diagram showing an example of the state of the oxygen concentrator during a period T3. [Figure 7] FIG. 1 is a diagram schematically illustrating an example of the overall configuration of an oxygen concentrator according to configuration CP1. [Figure 8] FIG. 10 is a diagram schematically illustrating an example of the overall configuration of an oxygen concentrator according to configuration CP2. [Figure 9] FIG. 10 is a diagram illustrating an example of the overall configuration of an oxygen concentrator according to configuration CP3. [Figure 10] FIG. 10 is a diagram illustrating an example of the overall configuration of an oxygen concentrator according to configuration CP4. [Figure 11] FIG. 10 is a diagram illustrating an example of the overall configuration of an oxygen concentrator according to configuration CP5. [Figure 12] FIG. 10 is a diagram showing an example of a comparison result C1. [Figure 13] FIG. 13 is a diagram showing an example of the maximum oxygen concentration corresponding to FIG. 12. [Figure 14] FIG. 13 is a diagram showing an example of the minimum value of the oxygen concentration corresponding to FIG. 12. [Figure 15] FIG. 10 is a diagram showing an example of a comparison result C2. [Figure 16] FIG. 10 is a diagram showing an example of a comparison result C3. [Figure 17] FIG. 10 is a diagram showing an example of a comparison result C4. [Figure 18] 10 is a timing chart showing a specific example of the flow of processing by the oxygen concentrator. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. To facilitate understanding of the description, the same components in the drawings will be denoted by the same reference numerals as much as possible, and duplicate descriptions will be omitted where appropriate.

[0023] ===First Embodiment=== <Overall structure> FIG. 1 is a diagram schematically illustrating an example of the overall configuration of an oxygen concentrator 1 according to a first embodiment of the present invention. The oxygen concentrator 1 is also called an oxygen gas generator or a PSA (Pressure Swing Adsorption). The oxygen concentrator 1 is a device that separates nitrogen and moisture from a gas to generate a gas with a high oxygen concentration. The gas is, for example, the air (outside air) in the surrounding environment of the oxygen concentrator 1. Note that the gas is not limited to the above as long as it contains oxygen. The gas may also contain acidic gases such as ozone gas and chlorine-based gases.

[0024] 1, the oxygen concentrator 1 mainly comprises an activated carbon filter 3, a solenoid valve V2, a compressor 5, a drain tank 6, a solenoid valve V1, an adsorption device 8, a feedback line L9, a circulation line L10, a bypass line L11, an orifice OR2, an air chamber 12, and a control device 13. Note that the specific configuration of the oxygen concentrator 1 is not limited to that shown in FIG.

[0025] The activated carbon filter 3 is provided at one end of the line L1, which serves as the first line. The activated carbon filter 3 is a filter member that uses activated carbon. For example, gas containing ozone gas or chlorine-based gas is taken in from the outside air as a raw gas through the activated carbon filter 3, and the ozone gas, chlorine-based gas, etc. are removed, and the gas is taken in the line L1. This makes it possible to suppress corrosion damage to resin materials used in the system. Furthermore, the oxygen concentrator 1 can be used in various environments, such as a swimming pool or a bathroom.

[0026] The solenoid valve V2 is an intake solenoid valve that connects the intake port 5a of the compressor 5 to either the line (first line) L1 or the circulation line L10. The solenoid valve V2 is a three-port type having ports NO, NC, and COM. Port NO is connected to the line L1, and port NC is connected to the circulation line L10 (described later). Port COM is connected to the line L2 (second line). The solenoid valve V2 opens either port NO or port NC to port COM. That is, when port NO is selected, the lines L1 and L2 are open, and when port NC is selected, the circulation line L10 and L2 are open. That is, depending on the state of the solenoid valve V2, it is controlled whether outside air is supplied to the compressor 5 via line L1 or gas and moisture from the adsorber 8 are supplied to the compressor 5 via the circulation line L10.

[0027] The compressor 5 takes in air and pressurizes (compresses) it. Specifically, the compressor 5 has an intake port 5a connected to a line L2, and takes in gas from, for example, a line L1 and pressurizes it. The gas pressurized by the compressor 5 is referred to as "compressed gas." The pressurized gas is discharged to a line L3, which serves as a third line connected to a discharge port 5b of the compressor 5.

[0028] The water drain tank 6 is connected to the middle of the line L3. That is, the water drain tank 6 is provided between the compressor 5 and the solenoid valve V1. The water drain tank 6 drains water from the pressurized gas flowing through the line L3. That is, the water drain tank 6 reduces the amount of moisture contained in the pressurized gas and discharges the pressurized gas to the solenoid valve V1. The removed moisture is temporarily accumulated in the water drain tank 6. The accumulated moisture is discharged by the solenoid valve V3. For example, the accumulated moisture is periodically discharged by the solenoid valve V3.

[0029] The solenoid valve V1 is supplied with pressurized gas discharged from the compressor 5 and switches the supply destination of the pressurized gas. The solenoid valve V1 is a four-port type (four-way, three-position type) and has ports P1, P2, P3, and P4. The solenoid valve V1 switches the connection states of the four ports. Specifically, the solenoid valve V1 switches between three connection states. In connection state S1, ports P1 and P3 are connected, and ports P2 and P4 are connected. In connection state S2, ports P3 and P4 are connected. In connection state S3, ports P1 and P4 are connected, and ports P2 and P3 are connected. The flow of gas is controlled by the solenoid valve V1. The example in FIG. 1 shows a case where the solenoid valve V1 is in connection state S2. The solenoid valve V1 is, for example, a pilot-operated valve.

[0030] The adsorption device 8 adsorbs nitrogen and moisture from pressurized gas. The adsorption device 8 includes a first adsorption unit 8A and a second adsorption unit 8B. The first adsorption unit 8A and the second adsorption unit 8B use an adsorbent, such as zeolite, to adsorb nitrogen and moisture from the pressurized gas supplied from one end of the adsorption device. The first adsorption unit 8A is connected to port P4 of the solenoid valve V1 via line L4, and the second adsorption unit 8B is connected to port P3 of the solenoid valve V1 via line L5. The first adsorption unit 8A and the second adsorption unit 8B have similar configurations, but are supplied with pressurized gas at different times. They alternate between an adsorption process and a regeneration process. The adsorption process adsorbs nitrogen and moisture from the pressurized gas and discharges the resulting oxygen-enriched gas. The oxygen-enriched gas produced in the adsorption process is a dry gas with a high oxygen concentration. The nitrogen and moisture adsorbed in the adsorption process are accumulated. In particular, when the gas compressed by the compressor 5 is in a high-temperature, high-humidity state, nitrogen and moisture are likely to accumulate. The regeneration process is a process in which the adsorbed and accumulated nitrogen and moisture are discharged as exhaust gas together with the supplied gas (oxygen-enriched gas). When the first adsorption section 8A or the second adsorption section 8B (one side) that performs the adsorption process becomes the "adsorption section," the second adsorption section 8B or the first adsorption section 8A (the other side) that performs the regeneration process on the opposite side becomes the "regeneration section." In other words, when the first adsorption section 8A is the adsorption section, the second adsorption section 8B becomes the regeneration section, and when the second adsorption section 8B is the adsorption section, the first adsorption section 8A becomes the regeneration section.

[0031] Whether the first adsorption unit 8A or the second adsorption unit 8B functions as an adsorption unit or a regeneration unit is controlled by the state of the solenoid valve V1. Specifically, of the first adsorption unit 8A and the second adsorption unit 8B, one that receives pressurized gas functions as an adsorption unit, and the other functions as a regeneration unit. That is, the adsorption units are pressurized by the compressor 5. When the solenoid valve V1 is in the connected state S1, the first adsorption unit 8A functions as a regeneration unit, and the second adsorption unit 8B functions as an adsorption unit. When the solenoid valve V1 is in the connected state S3, the first adsorption unit 8A functions as an adsorption unit, and the second adsorption unit 8B functions as a regeneration unit. When the solenoid valve V1 is in the connected state S2, neither the first adsorption unit 8A nor the second adsorption unit 8B functions as an adsorption unit or a regeneration unit, and they are in a pressure-equalizing state. Creating a pressure-equalizing state stabilizes the oxygen concentration. For example, the pressure-equalizing state (connected state S2) should last for about one second.

[0032] The first adsorption unit 8A is connected to a line L6 provided with a check valve 17A serving as a first check valve. The check valve 17A has a primary side on the side of the first adsorption unit 8A and a secondary side on the opposite side. When the pressure on the primary side is higher than the pressure on the secondary side, the check valve 17A allows gas to flow from the primary side to the secondary side and prevents backflow from the secondary side to the primary side. The second adsorption unit 8B is connected to a line L7 provided with a check valve 17B serving as a second check valve. The check valve 17B has a primary side on the side of the second adsorption unit 8B and a secondary side on the opposite side. When the pressure on the primary side is higher than the pressure on the secondary side, the check valve 17B allows gas to flow from the primary side to the secondary side and prevents backflow from the secondary side to the primary side. Note that the smaller the pressure difference between the primary and secondary sides, the more likely backflow will occur in the check valves 17A and 17B. For this reason, as will be described later, the provision of orifice OR2 makes it easier to clearly create a differential pressure between the primary and secondary sides of check valve 17A and check valve 17B, thereby effectively preventing backflow. Specifically, the provision of orifice OR2 prevents the secondary pressure of check valve 17A and check valve 17B from becoming too low (approaching the primary pressure), effectively preventing backflow. The secondary side of check valve 17A on line L6 and the secondary side of check valve 17B on line L7 join together and are connected to line L8.

[0033] The feedback line L9 connects the line L6 and the line L7. Specifically, the feedback line L9 connects the other end of the first adsorption unit 8A to the other end of the second adsorption unit 8B. That is, the feedback line L9 connects the first adsorption unit 8A and the check valve 17A to the second adsorption unit 8B and the check valve 17B. A portion of the oxygen-enriched gas discharged from either the first adsorption unit 8A or the second adsorption unit 8B is fed back to the other. The feedback line L9 is provided with an orifice OR1 as a first orifice, which limits the flow rate (pressure) of the gas flowing through the feedback line L9.

[0034] For example, when the solenoid valve V1 is in the connected state S1, the oxygen-enriched gas generated in the second adsorption unit 8B serving as an adsorption unit flows through line L7 to line L8, and a portion of the oxygen-enriched gas in line L7 flows through feedback line L9. This causes the oxygen-enriched gas generated in the second adsorption unit 8B serving as an adsorption unit to be fed back to the first adsorption unit 8A serving as a regeneration unit. Because the pressure in the primary side of the check valve 17B is higher than that in the secondary side, the check valve 17B sends the oxygen-enriched gas generated in the second adsorption unit 8B to the air chamber 12 (described below). Because the pressure in the primary side of the check valve 17A is lower than that in the secondary side, backflow from the secondary side to the primary side is suppressed. Therefore, the oxygen-enriched gas that has passed through feedback line L9 does not flow from the check valve 17A to line L8 but instead flows into the first adsorption unit 8A. As a result, the oxygen-enriched gas that flows in from the end of the first adsorption section 8A on the check valve 17A side flows out as exhaust gas from the end of the first adsorption section 8A on the solenoid valve V1 side together with the accumulated nitrogen and moisture. The exhaust gas is circulated by the solenoid valve V1 to a circulation line L10, which will be described later.

[0035] One end of the circulation line L10 is connected to port P2 of the solenoid valve V1, and the other end is connected to port NC of the solenoid valve V2. The circulation line L10 supplies the exhaust gas discharged from the regeneration unit to the intake side of the compressor 5. Specifically, when the solenoid valve V1 is in the connected state S1, the exhaust gas discharged from the first adsorption unit 8A flows into the circulation line L10. On the other hand, when the solenoid valve V1 is in the connected state S3, the exhaust gas discharged from the second adsorption unit 8B flows into the circulation line L10. The gas in the regeneration unit is actively extracted by the compressor 5 at a pressure lower than atmospheric pressure. The exhaust gas supplied to the compressor 5 via the circulation line L10 is pressurized in the compressor 5 and then supplied again to the adsorption device 8. In this way, the exhaust gas circulates through the system via the circulation line L10.

[0036] Furthermore, the circulation line L10 is provided with a line L12. The line L12 releases the exhaust gas flowing through the circulation line L10 via a silencer 20. A check valve 21 is provided in the line L12 between the circulation line L10 and the silencer 20, with the circulation line L10 side being the primary side and the silencer 20 side being the secondary side, and when the pressure on the primary side is higher than the pressure on the secondary side, the check valve 21 allows the gas to flow from the primary side to the secondary side and prevents backflow from the secondary side to the primary side.

[0037] The bypass line L11 connects the line L1 and the circulation line L10. Specifically, the bypass line L11 connects the activated carbon filter 3 and the solenoid valve V2 in the line L1 to the solenoid valve V2 and the solenoid valve V1 in the circulation line L10. The bypass line L11 supplies gas (outside air) from the line L1 to the circulation line L10. The bypass line L11 is provided with a check valve 22 and an orifice OR3. The check valve 22 has the line L1 as its primary side and the circulation line L10 as its secondary side. When the pressure on the primary side is higher than the pressure on the secondary side, the check valve 22 allows gas to flow from the primary side to the secondary side and prevents backflow from the secondary side to the primary side. For example, the pressure on the circulation line L10 on the secondary side of the check valve 22 is suctioned by the compressor 5 and becomes lower than atmospheric pressure (e.g., the primary side of the check valve 22), allowing gas to flow from the primary side to the secondary side. The orifice OR3 adjusts the amount of gas supplied from the bypass line L11 to the circulation line L10 so as to supplement the amount of exhaust gas circulating through the circulation line L10 to the compressor 5. The orifice diameter of the orifice OR3 is, for example, about 1.0 to 1.6 mm. That is, the check valve 22 allows gas to flow from the line L1 to the circulation line L10, and the orifice OR3 adjusts the amount of gas flow, allowing an appropriate amount of gas to circulate to the compressor 5.

[0038] In this way, the exhaust gas discharged from the regeneration unit flows into the circulation line L10, and at the same time, gas (outside air) is supplied from the bypass line L11 to the circulation line L10 via the activated carbon filter 3, and the gas amounts are summed and flow to the compressor 5. As a result, not only the exhaust gas but also the outside air flows to the compressor 5, which prevents a shortage of the overall gas amount and ensures the production amount of oxygen-enriched gas.

[0039] Orifice OR2 is provided in line L8 as a second orifice. Specifically, orifice OR2 is provided between the air chamber 12 and the junction (confluence) of lines L6 and L7. Orifice OR2 limits the flow rate (pressure) of the gas flowing through line L8. Orifice OR2 also adjusts the pressure on the secondary side of check valve 17A and the pressure on the secondary side of check valve 17B.

[0040] The orifice diameter of orifice OR2 is preferably equal to or larger than the orifice diameter of orifice OR1. Check valves 17A and 17B open when the pressure on the primary side is higher than the pressure on the secondary side and close when the pressure on the primary side is lower than the pressure on the secondary side. However, when the pressure difference between the primary and secondary sides of check valves 17A and 17B is small, i.e., when the pressure on the primary side and the pressure on the secondary side are equal (or nearly equal), gas may flow from both directions, preventing the check valves 17A and 17B from functioning as a check valve. For example, when solenoid valve V1 is switched between the adsorption and regeneration sections of first adsorption section 8A and second adsorption section 8B, the pressure on the primary side and the pressure on the secondary side may fluctuate, temporarily causing a small pressure difference between the primary and secondary sides. Specifically, when the solenoid valve V1 is in the connected state S1, the oxygen-enriched gas generated in the second adsorption unit 8B flows to the first adsorption unit 8A. However, when the solenoid valve V1 is switched, for example, a pressure fluctuation occurs between the first adsorption unit 8A and the check valve 17A, which may cause backflow at the check valve 17A. Specifically, before switching, the oxygen-enriched gas discharged from the second adsorption unit 8B flows through lines L7 and L8, and the pressures in lines L7 and L8 are high. In addition, some of the oxygen-enriched gas discharged from the second adsorption unit 8B flows to line L6 through feedback line L9, but the flow rate is limited by orifice OR1. Furthermore, the oxygen-enriched gas flowing to line L6 is drawn into the compressor 5 via the first adsorption unit 8A, so the pressure in line L6 (the upstream side of the check valve 17A) is low. On the other hand, because the oxygen-enriched gas in line L8 is discharged by regulator 24, if there is no gas supply from line L7, the pressure on the secondary side of check valve 17A is also likely to drop. In particular, when solenoid valve V1 is switched, the amount of gas fed back is limited, so the increase in pressure on line L6 (the primary side of check valve 17A) is small. That is, particularly when solenoid valve V1 is switched, the pressure drops due to the limited amount of gas on the primary side of check valve 17A, and the discharge of oxygen-enriched gas in line L8 also tends to lower the pressure on the secondary side of check valve 17A. That is, the pressure difference between the primary and secondary sides of check valve 17A becomes small, which may cause backflow.When a backflow occurs in this way, the oxygen-enriched gas on the line L8 side flows to the primary side of the check valve 17A, and the amount of oxygen-enriched gas sent to the air chamber 12 decreases.

[0041] For this reason, orifices OR2 are provided on the secondary side of check valves 17A and 17B to suppress pressure fluctuations. Specifically, orifices OR2 prevent the pressure on the secondary side of check valves 17A and 17B from becoming too low, thereby preventing backflow at check valves 17A and 17B. Specifically, the pressure drops on the air chamber 12 side of orifice OR2 as oxygen-enriched gas is discharged from regulator 24, but the pressure remains high on the junction side of orifice OR2, preventing backflow at check valves 17A and 17B. This prevents backflow of the oxygen-enriched gas after passing through the adsorption section, allowing the oxygen-enriched gas to be stably delivered to air chamber 12. To adjust the pressure, the orifice diameter of orifice OR2 is preferably equal to or larger than the orifice diameter of orifice OR1. By preventing backflow, a decrease in the amount of oxygen-enriched gas delivered to air chamber 12 is suppressed.

[0042] FIG. 2 is a diagram showing an example of a comparison of the orifice diameters of orifices OR1 and OR2. FIG. 2 shows patterns PT1 to PT4, each representing a combination of the orifice diameters of orifices OR1 and OR2. Specifically, in pattern PT1, orifice OR1 is 0.7 mm and orifice OR2 is 0.6 mm. In pattern PT2, orifice OR1 is 0.7 mm and orifice OR2 is 0.7 mm. In pattern PT3, orifice OR1 is 0.6 mm and orifice OR2 is 0.7 mm. In pattern PT4, orifice OR1 is 0.5 mm and orifice OR2 is 1.0 mm. FIG. 2 also shows an overall evaluation of the oxygen concentration of the oxygen-enriched gas discharged from regulator 24 and the change (fluctuation) in the discharge pressure. The evaluations are expressed in three patterns: "×", "△", and "〇", with "×", "△", and "〇" indicating better evaluations in that order ("〇" being the best evaluation).

[0043] As shown in Figure 2, pattern PT1 results in a low oxygen concentration and a large change in discharge pressure, resulting in an overall rating of "×." Pattern PT2 may result in a low oxygen concentration, resulting in an overall rating of "△." Pattern PT3 may result in a high oxygen concentration and a small change in discharge pressure, resulting in an overall rating of "〇." Pattern PT4 may result in a low oxygen concentration, resulting in an overall rating of "△." This is thought to be due to the fact that if the orifice diameter of orifice OR2 is too small compared to orifice OR1, the flow rate of the oxygen-enriched gas decreases, making it difficult to maintain pressure and increasing the amount of oxygen-enriched gas fed back. For example, if the orifice diameter of orifice OR2 is too small, it is difficult for oxygen-enriched gas to be discharged from orifice OR2 to air chamber 12, which tends to increase the pressure upstream of orifice OR2. Note that check valves such as 17A do not allow gas to flow to line L8 unless the pressure on the primary side exceeds the pressure on the secondary side. As a result, oxygen-enriched gas flows through the feedback line L9, increasing the amount of oxygen-enriched gas fed back. On the other hand, if the orifice diameter of orifice OR2 is too large relative to orifice OR1, it becomes difficult to maintain oxygen-enriched gas upstream of orifice OR2, resulting in a drop in pressure. This means that the pressure on the secondary side of check valve 17A or check valve 17B is likely to be low. Furthermore, if the orifice diameter of orifice OR1 is small, for example, less oxygen-enriched gas is fed back from second adsorption section 8B to first adsorption section 8A, making it difficult for the pressure on the first adsorption section 8A side to increase. This means that the pressure on the primary side of check valve 17A is unlikely to increase. This reduces the pressure difference between the primary and secondary sides of check valve 17A, making backflow more likely to occur, resulting in a slight decrease in oxygen concentration. Based on these results, it is preferable that the orifice diameter of orifice OR2 be equal to or larger than the orifice diameter of orifice OR1. By making the orifice diameter of orifice OR2 larger than or equal to the orifice diameter of orifice OR1, the oxygen concentration and discharge pressure change rate can be improved compared to when the orifice diameter of orifice OR2 is smaller than the orifice diameter of orifice OR1. In particular, based on the results in Figure 2, it is preferable that the ratio of the orifice diameter of orifice OR2 to the orifice diameter of orifice OR1 is greater than 1 and less than 2.In other words, the orifice diameter of orifice OR2 is preferably larger than the orifice diameter of orifice OR1 but smaller than twice the orifice diameter of orifice OR1. By setting the orifice diameter within this range, a high oxygen concentration and a small change in discharge pressure can be achieved. For example, the orifice diameter of orifice OR2 is 0.7 mm, and the orifice diameter of orifice OR1 is 0.6 mm.

[0044] Furthermore, gas tends to have a strong pressure cushioning effect. For this reason, it is preferable to provide the orifice OR2 in a position on the line L8 closer to the confluence of the lines L6 and L7 than the air chamber 12. Specifically, it is preferable to provide the orifice OR2 closer to the confluence than the midpoint that divides the entire length of the line L8 between the air chamber 12 and the confluence of the lines L6 and L7.

[0045] FIG. 3 shows an example of the relationship between the oxygen concentration and flow rate of oxygen-enriched gas depending on the position of orifice OR2. In FIG. 3, graph D1 shows the case where orifice OR2 is installed at the position shown in FIG. 1 (close to the confluence), graph D2 shows the case where orifice OR2 is installed upstream of air chamber 12, and graph D3 shows a reference example where orifice OR2 is not installed. As shown in FIG. 3, compared to the case where orifice OR2 is not installed (graph D3), the case where orifice OR2 is installed upstream of air chamber 12 (graph D2) ensures a higher oxygen concentration and flow rate. Furthermore, compared to the case where orifice OR2 is installed upstream of air chamber 12 (graph D2), the case where orifice OR2 is installed at the position shown in FIG. 1 (graph D1) ensures a higher oxygen concentration and flow rate. This is because orifice OR2 adjusts the pressure on the secondary side of check valve 17A or check valve 17B, thereby suppressing backflow. Specifically, gas has a cushioning effect, and if orifice OR2 is located farther from the confluence, the volume of the path from check valve 17A or check valve 17B to orifice OR2 increases. As the volume increases, the cushioning effect tends to reduce the flow rate. To effectively suppress pressure fluctuations on the secondary side of check valve 17A or check valve 17B against the cushioning effect, orifice OR2 is preferably located closer to the confluence than air chamber 12 on line L8. The closer orifice OR2 is located to the confluence, the more preferable it is.

[0046] Returning to FIG. 1 , the air chamber 12 is connected downstream of the line L8 and is supplied with oxygen-enriched gas discharged from the adsorption section of the adsorption device 8. A regulator 24 is provided downstream of the air chamber 12, and the oxygen-enriched gas is discharged to the outside via the regulator 24. The regulator 24 controls the pressure of the oxygen-enriched gas being discharged to the outside. By providing an orifice OR2, it is possible to use a relief type regulator 24. A relief type regulator 24 consumes gas for control, but the orifice OR2 suppresses a decrease in the amount of oxygen-enriched gas, so a stable amount of oxygen-enriched gas can be maintained while a stable discharge pressure can be obtained.

[0047] The control device 13 is an information processing device (computer) that controls each part of the oxygen concentrator 1.

[0048] Specifically, the control device 13 controls the solenoid valve V1 to supply pressurized gas to the adsorption unit. That is, the control device 13 switches the connection state of the solenoid valve V1. The control device 13 controls the solenoid valve V1 to supply pressurized gas to either the first adsorption unit 8A or the second adsorption unit 8B. Then, the oxygen-enriched gas discharged from the adsorption unit is supplied to the other regeneration unit (the first adsorption unit 8A or the second adsorption unit 8B) via the feedback line L9. Then, during the period in which the pressurized gas is being supplied, the control device 13 controls the solenoid valve V2 to switch from a state in which the line L2 (the intake port 5a of the compressor 5) and the circulation line L10 are connected to a state in which the line L2 and the line L1 are connected. For example, when the solenoid valve V1 is controlled to set the first adsorption unit 8A as the regeneration unit, the control device 13 controls the solenoid valve V2 to switch from a state in which the line L2 and the circulation line L10 are connected to a state in which the line L2 and the line L1 are connected.

[0049] 1, the control device 13 includes a control unit 30, a communication unit 31, and a storage unit 32. The control unit 30 mainly includes a CPU (Central Processing Unit) 33 and a memory .

[0050] In the control unit 30, the CPU 33 executes predetermined programs stored in the memory 34 or the storage unit 32, etc., thereby functioning as various functional components described below. The memory 34 is a computer-readable storage medium, and may be composed of at least one of, for example, a random access memory (RAM), a read-only memory (ROM), an erasable program read-only memory (EPROM), an electrically erasable program read-only memory (EEPROM), etc. The memory 34 can store various types of data, such as programs required to execute processing.

[0051] The communication unit 31 is configured with a communication interface for communicating with an external device.

[0052] The storage unit 32 is a computer-readable instruction recording medium, and is configured, for example, with a hard disk or a solid state drive. The storage unit 32 stores various programs and information required for executing processes in the control unit 30, as well as information on the processing results. Note that other examples of non-transitory computer-readable instruction recording media include portable recording media such as magnetic tape, flexible disks, optical disks, digital versatile disks, Blu-ray disks, magneto-optical disks, memory cards, and USB memory.

[0053] The control device 13 can also be realized using an information processing device such as a dedicated or general-purpose computer or a microcomputer. The control device 13 may be configured with a single information processing device or multiple information processing devices. FIG. 1 only shows a portion of the main hardware configuration of the control device 13, and the control device 13 may have other configurations. For example, the control device 13 may further include an input unit (not shown) and a display unit (not shown). The input unit is an input device (e.g., a keyboard, a mouse, etc.) that accepts input from the outside. The input unit accepts user operations and inputs the operations to the control device 13. The display unit is a display device (e.g., a display, etc.) that outputs to the outside. The display unit outputs characters and images. The control device 13 may have an input unit and a display unit integrated together (e.g., a touch panel).

[0054] <Processing flow> Fig. 4 is a timing chart (time chart) showing an example of the processing flow of the oxygen concentrator 1 according to this embodiment. Fig. 4 shows the operation of each part in chronological order. Fig. 4 shows the state of solenoid valve V1, the state of solenoid valve V2, the state of first adsorption unit 8A, the state of second adsorption unit 8B, and the state of solenoid valve V3.

[0055] The solenoid valve V1 is controlled to switch between a connected state S1, a connected state S2, and a connected state S3. The solenoid valve V2 is controlled to switch between a state in which port NO is selected and a state in which port NC is selected. The first adsorption unit 8A is controlled to switch between an adsorption process, a pressure equalization process, and a regeneration process. The second adsorption unit 8B is controlled to switch between an adsorption process, a pressure equalization process, and a regeneration process. The solenoid valve V3 is controlled to switch between ON and OFF.

[0056] During period T1, the solenoid valve V1 is in the connected state S3, which causes the first adsorption unit 8A to perform the adsorption process and the second adsorption unit 8B to perform the regeneration process. Figure 5 shows the state of the oxygen concentrator 1 during period T1 (specifically, period T2). Pressurized gas is supplied to the first adsorption unit 8A, and oxygen-enriched gas is generated in the first adsorption unit 8A and supplied to the air chamber 12. A portion of the oxygen-enriched gas generated in the first adsorption unit 8A is fed back from the first adsorption unit 8A to the second adsorption unit 8B. During period T2 (e.g., approximately 5 to 20 seconds), which is the first half of period T1, port NC is selected by the solenoid valve V2. The exhaust gas from the second adsorption unit 8B is actively drawn (sucked) by the compressor 5, and the oxygen-enriched gas for regeneration flows to the second adsorption unit 8B, restoring the adsorption function. Furthermore, ambient air is supplied to the circulation line L10 via the bypass line L11, preventing a decrease in the amount of oxygen-enriched gas generated (the amount of gas produced). Returning to Figure 4, when the period moves to period T3, which is the latter half of period T1, the state of solenoid valve V2 switches. Figure 6 shows the state of the oxygen concentrator 1 during period T1 (specifically, period T3). During period T3 (for example, about 5 to 10 seconds), port NO is selected in solenoid valve V2, and the exhaust gas does not circulate, with only outside air being supplied to compressor 5 through line L1. The exhaust gas is released outside the system via line L12.

[0057] 4, during a period T4 (for example, about 2 seconds), the solenoid valve V1 switches to the connected state S2. The first adsorption portion 8A and the second adsorption portion 8B are opened, and the pressure states are equalized.

[0058] For example, immediately after the connection state of solenoid valve V1 is switched, there is a possibility that the differential pressure between the primary pressure and secondary pressure of check valve 17A and check valve 17B will fluctuate significantly. If the differential pressure approaches zero, backflow may occur, but orifice OR2 suppresses the pressure fluctuations on the secondary sides of check valve 17A and check valve 17B. This prevents backflow from occurring.

[0059] Then, when the period T4 transitions to period T5, the solenoid valve V1 transitions to the connected state S1. Accordingly, the second adsorption unit 8B enters the adsorption process, and the first adsorption unit 8A enters the regeneration process. Therefore, oxygen-enriched gas is generated in the second adsorption unit 8B and supplied to the air chamber 12. During period T6, which is the first half of period T5, port NC is selected in the solenoid valve V2, and the adsorption function of the first adsorption unit 8A is restored. Furthermore, outside air is supplied to the circulation line L10 via the bypass line L11, suppressing a decrease in the amount of oxygen-enriched gas generated. Then, during period T7, which is the second half of period T5, the state of the solenoid valve V2 switches. During period T7, port NO is selected in the solenoid valve V2, and only outside air is supplied to the compressor 5 via line L1.

[0060] The above steps are repeated, and the adsorption step and the regeneration step are alternately carried out in the first adsorption section 8A and the second adsorption section 8B.

[0061] Furthermore, as shown in period T8, the solenoid valve V3 is periodically turned on, and the moisture accumulated in the drain tank 6 is drained to the outside. For example, the moisture is drained for about 1 to 5 seconds every 10 to 30 minutes.

[0062] <Action and effect> As described above, in this embodiment, the oxygen concentrator 1 includes a line L1 as a first line, a compressor 5 that draws in and pressurizes gas via the line L1, a solenoid valve V1 that receives the pressurized gas discharged from the compressor 5 and switches the supply destination of the pressurized gas, a first adsorption unit 8A that receives the pressurized gas from one end thereof via the solenoid valve V1 and adsorbs nitrogen and moisture from the pressurized gas, a second adsorption unit 8B that receives the pressurized gas from one end thereof via the solenoid valve V1 and adsorbs nitrogen and moisture from the pressurized gas, a check valve 17A that is provided at the other end of the first adsorption unit 8A and serves as a first check valve with the first adsorption unit 8A side as its primary side, and a second check valve that is provided at the other end of the second adsorption unit 8B and serves as a check valve with the second adsorption unit 8B side as its primary side. The system is equipped with a check valve 17B as a stop valve, a feedback line L9 connecting between the first adsorption section 8A and the check valve 17A and between the second adsorption section 8B and the check valve 17B, a control device 13 that controls the solenoid valve V1 to supply pressurized gas to either the first adsorption section 8A or the second adsorption section 8B and supplies oxygen-enriched gas discharged from that adsorption section to the other of the first adsorption section 8A or the second adsorption section 8B via the feedback line L9, an orifice OR1 as a first orifice provided in the feedback line L9, and an orifice OR2 as a second orifice provided downstream of the confluence of the secondary line of the check valve 17A and the secondary line of the check valve 17B.

[0063] According to this configuration, in a configuration in which the first adsorption unit 8A and the second adsorption unit 8B are switched between operation by the solenoid valve V1, fluctuations in the pressure difference between the primary side and secondary side of the check valve 17A or the check valve 17B can be suppressed by the orifice OR2. This suppresses backflow in the check valve 17A or the check valve 17B, and prevents a decrease in the amount of oxygen-enriched gas produced. In other words, the discharge amount of oxygen-enriched gas can be stabilized. Furthermore, because backflow is suppressed, it is also possible to increase the discharge amount of oxygen-enriched gas.

[0064] In this embodiment, the orifice diameter of the orifice OR2 is equal to or larger than the orifice diameter of the orifice OR1.

[0065] This configuration can prevent backflow at check valves 17A and 17B while suppressing a decrease in the discharge amount of oxygen-enriched gas (the amount discharged toward air chamber 12). For example, if the orifice diameter of orifice OR2 is smaller than the orifice diameter of orifice OR1, the oxygen concentration of the discharged oxygen-enriched gas may be low and the amount of change in discharge pressure may be large.

[0066] In this embodiment, the ratio of the orifice diameter of the orifice OR2 to the orifice diameter of the orifice OR1 is greater than 1 and less than 2.

[0067] According to this configuration, it is possible to suppress the amount of change in the discharge pressure while increasing the oxygen concentration.

[0068] In this embodiment, the orifice OR2 is provided on the line between the confluence and the air chamber 12 provided downstream of the confluence, at a position closer to the confluence than the air chamber 12.

[0069] This configuration can effectively suppress pressure fluctuations at check valves 17A and 17B compared to, for example, providing orifice OR2 closer to air chamber 12. This suppresses backflow and reduces the reduction in the amount of oxygen-enriched gas discharged.

[0070] === Second Embodiment === Next, a second embodiment will be described.

[0071] In the second embodiment, a specific example of the position where the orifice OR2 is provided will be described. Note that a description of the same points as in the first embodiment will be omitted. Also, the second embodiment can be combined with the first embodiment.

[0072] <Configuration pattern of oxygen concentrator 1> In this embodiment, five different configurations of the oxygen concentrator 1 will be described. In this embodiment, the different configurations will be described as configuration CP1, configuration CP2, configuration CP3, configuration CP4, and configuration CP5.

[0073] (Oxygen concentrator 1 of configuration CP1) 7 is a diagram schematically illustrating an example of the overall configuration of the oxygen concentrator 1 according to the configuration CP1. The configuration CP1 differs from the configuration example in FIG. 1 particularly in the installation position of the orifice OR2 in the oxygen concentrator 1.

[0074] 7, in configuration CP1, orifice OR2 is provided between check valves 17A and 17B and air chamber 12, and at a position closer to check valves 17A and 17B than to air chamber 12. Specifically, orifice OR2 is provided on the lines (lines L6, L7, and L8) between check valves 17A and 17B and air chamber 12, at a position closer to check valves 17A and 17B than to the midpoint that divides the entire length of the lines into two equal parts.

[0075] 7, in this embodiment, line L6 on the secondary side of check valve 17A and line L7 on the secondary side of check valve 17B join at a joining member 41 serving as a joining point and are connected to the air chamber 12 via line L8. Line L6 is a line that continues from the first adsorption portion 8A to the joining point, line L7 is a line that continues from the second adsorption portion 8B to the joining point, and line L8 is a line that continues from the joining point to the air chamber 12. The joining member 41 is a member that joins line L6 and line L7 and connects them to line L8. For this reason, orifices OR2 are provided between the secondary sides of check valves 17A and 17B and the joining point, on the secondary sides of check valves 17A and 17B, respectively. That is, an orifice OR2 is provided on line L6 on the secondary side of check valve 17A and on line L7 on the secondary side of check valve 17B. Preferably, the orifices OR2 provided on each line have the same specifications. Alternatively, the junction may be omitted, and line L6 and line L7 may each lead directly to air chamber 12 without merging.

[0076] Furthermore, it is more preferable that the orifice OR2 be provided in the vicinity of each of the check valves 17A and 17B (immediately after the check valves 17A and 17B). Specifically, it is preferable that the orifice OR2 be connected to each of the check valves 17A and 17B. For example, it is preferable that the orifice OR2 be provided in a connection port on the secondary side of the check valve 17A. In this case, the orifice OR2 is fixedly provided in the connection port on the secondary side of the check valve 17A. In other words, it is preferable that the orifice OR2 be provided at the end of the secondary side of the check valve 17A (the end of the line L6 on the secondary side of the check valve 17A). Note that, similarly to the above, an orifice OR2 is also provided in the check valve 17B. In this way, it is preferable that the orifice OR2 be directly connected to each of the check valves 17A and 17B. For example, orifice OR2 is inserted into a tube or built into a fitting (including the case where the fitting itself is the orifice), and is then screwed into check valve 17A or check valve 17B and connected to check valve 17A or check valve 17B.

[0077] In this embodiment, the case where line L6 on the secondary side of check valve 17A and line L7 on the secondary side of check valve 17B join at a joining point has been exemplified, but line L6 and line L7 may each extend and be connected to air chamber 12. In this case, in configuration CP1, orifice OR2 may be provided between check valves 17A and 17B and air chamber 12, and at a position closer to check valves 17A and 17B than to air chamber 12.

[0078] 7, an orifice OR4 is provided in line L12 on the secondary side of check valve 21. Line L12 is a line that discharges gas in circulation line L10 to the outside of the system via check valve 21, and the provision of orifice OR4 limits the flow rate of exhaust gas discharged from line L12. Note that in line L12, orifice OR4 may be omitted and silencer 20 may be provided instead, as in FIG. 1, or both orifice OR4 and silencer 20 may be provided.

[0079] As described above, it is possible to configure the oxygen concentrator 1 as in the configuration CP1.

[0080] (Oxygen concentrator 1 of configuration CP2) Fig. 8 is a diagram schematically illustrating an example of the overall configuration of the oxygen concentrator 1 according to the configuration CP2. In the configuration CP2, the installation position of the orifice OR2 in the oxygen concentrator 1 is the same as in the configuration example of Fig. 1. Note that in the configuration CP2, the configuration other than the position of the orifice OR2 is the same as in the configuration CP1.

[0081] As shown in FIG. 8, in the configuration CP2, the orifice OR2 is provided between the check valves 17A and 17B and the air chamber 12. As shown in FIG. 8, in the configuration CP2, the line L6 on the secondary side of the check valve 17A and the line L7 on the secondary side of the check valve 17B join at a joining point (joining member 41) and are connected to the air chamber 12 via the line L8. Therefore, the orifice OR2 is provided on the line L8 between the joining point and the air chamber 12. The orifice OR2 is provided at a position on the line L8 closer to the joining point than the air chamber 12. Specifically, the orifice OR2 is provided on the line L8 between the joining point of the secondary sides of the check valves 17A and 17B and the air chamber 12, at a position closer to the joining point than the midpoint dividing the entire length of the line L8.

[0082] Furthermore, it is more preferable that the orifice OR2 be provided close to the junction point (immediately after the junction point). Specifically, it is preferable that the orifice OR2 be connected to the junction member 41 that constitutes the junction point. For example, it is preferable that the orifice OR2 be provided at the connection port on the line L8 side of the junction member 41. In this case, the orifice OR2 is fixedly provided at the connection port on the line L8 side of the junction member 41. In other words, it is preferable that the orifice OR2 be provided at the end of the junction member 41 on the line L8 side (the end on the line L8 side). In this way, it is preferable that the orifice OR2 be directly connected to the junction member 41 that constitutes the junction point. For example, the orifice OR2 is inserted into a tube or built into a joint (including when the joint itself serves as an orifice), and is screwed into the junction member 41 that constitutes the junction point and connected to the junction member 41.

[0083] As described above, it is possible to configure the oxygen concentrator 1 as in the configuration CP2.

[0084] (Oxygen concentrator 1 of configuration CP3) 9 is a diagram schematically illustrating an example of the overall configuration of the oxygen concentrator 1 according to the configuration CP3. The configuration CP3 differs from the configuration example in FIG. 1, particularly in the installation position of the orifice OR2 in the oxygen concentrator 1. Note that the configuration CP3 is the same as the configuration CP1 except for the position of the orifice OR2.

[0085] 9, in configuration CP3, orifice OR2 is provided between check valves 17A and 17B and air chamber 12, and at a position closer to air chamber 12 than check valves 17A and 17B. Specifically, orifice OR2 is provided on the lines between check valves 17A and 17B and air chamber 12 (line L6 on the secondary side of check valve 17A, line L7 on the secondary side of check valve 17B, and line L8), at a position closer to air chamber 12 than the midpoint dividing the entire length of the lines. Note that, in the case where the confluence is omitted, orifice OR2 is provided on the lines between check valves 17A and 17B and air chamber 12, at a position closer to air chamber 12 than the midpoint dividing the entire length of the lines. In addition, when the confluence is omitted, the lines between the check valves 17A and 17B and the air chamber 12 are lines in which the secondary side line L6 of the check valve 17A and the secondary side line L7 of the check valve 17B each extend to the air chamber 12.

[0086] 9, line L6 on the secondary side of check valve 17A and line L7 on the secondary side of check valve 17B join at a joining member 41 serving as a joining point and are connected to air chamber 12 via line L8. For this reason, orifice OR2 is provided on line L8 between the joining point and air chamber 12. Orifice OR2 is provided at a position on line L8 closer to air chamber 12 than the joining point. Specifically, orifice OR2 is provided on line L8 between the air chamber 12 and the joining point of the secondary sides of check valve 17A and check valve 17B, at a position closer to air chamber 12 than the midpoint dividing the entire length of line L8.

[0087] Furthermore, it is more preferable that the orifice OR2 be provided close to the air chamber 12 (just before the air chamber 12). Specifically, it is preferable that the orifice OR2 be connected to the air chamber 12. For example, it is preferable that the orifice OR2 be provided at the connection port on the line L8 side of the air chamber 12. In this case, the orifice OR2 is fixedly provided at the connection port on the line L8 side of the air chamber 12. In other words, it is preferable that the orifice OR2 be provided at the end of the air chamber 12 on the line L8 side (the end of the line L8 on the air chamber 12 side). In this way, it is preferable that the orifice OR2 be directly connected to the air chamber 12. For example, the orifice OR2 is connected to the air chamber 12 by being inserted into a tube or built into a joint (including cases where the joint itself serves as the orifice) and screwed into the air chamber 12.

[0088] In this embodiment, the case where line L6 on the secondary side of check valve 17A and line L7 on the secondary side of check valve 17B join at a joining point has been exemplified, but line L6 and line L7 may each extend to and be connected to air chamber 12. In this case, in configuration CP3, orifices OR2 may each be provided between check valve 17A and check valve 17B and air chamber 12, and at positions closer to air chamber 12 than check valve 17A and check valve 17B. The orifices OR2 provided in each of the orifices preferably have the same specifications.

[0089] As described above, the oxygen concentrator 1 can be configured as in configuration CP3. In any of configurations CP1 to CP3, the orifice OR2 is on the secondary side of the check valves 17A and 17B, and is provided between the check valves 17A and 17B and the air chamber 12.

[0090] (Oxygen concentrator 1 of configuration CP4) FIG. 10 is a diagram schematically illustrating an example of the overall configuration of the oxygen concentrator 1 according to configuration CP4. Configuration CP4 is a reference example in which the orifice OR2 in the oxygen concentrator 1 is omitted. Specifically, in the reference example of configuration CP4 as shown in FIG. 10, the orifice OR2 is not provided between the check valves 17A and 17B and the air chamber 12. Note that configuration CP4 is identical to configuration CP1 in all respects except for the presence or absence of the orifice OR2.

[0091] (Oxygen concentrator 1 of configuration CP5) 11 is a diagram schematically illustrating an example of the overall configuration of the oxygen concentrator 1 according to the configuration CP5. The configuration CP5 shows an example of a configuration in which the orifice OR2 is replaced with an alternative member. Note that the configuration CP5 is identical to the configuration CP1 except for the alternative member.

[0092] In this embodiment, the alternative member is a flow rate adjustment pipe TB1. The flow rate adjustment pipe TB1 is a pipe for adjusting the flow rate, and more specifically, it limits the flow rate. In other words, the flow rate is suppressed by the flow rate adjustment pipe TB1.

[0093] As shown in FIG. 11 , in the configuration CP5, the flow rate adjustment pipe TB1 is provided between the check valves 17A and 17B and the air chamber 12. Specifically, the flow rate adjustment pipe TB1 is provided in the line between the check valves 17A and 17B and the air chamber 12. In this embodiment, as shown in FIG. 11 , the line L6 on the secondary side of the check valve 17A and the line L7 on the secondary side of the check valve 17B join at a joining member 41 serving as a joining point and are connected to the air chamber 12 via a line L8. Therefore, the flow rate adjustment pipe TB1 is provided on the line L8 between the joining point and the air chamber 12. Note that in the configuration CP5, no orifice OR2 is provided between the check valves 17A and 17B and the air chamber 12.

[0094] In other configurations (configurations CP1 to CP4), line L6, line L7, line L8, and feedback line L9 are configured using pipes with the same diameter (inner diameter and outer diameter), for example. Therefore, the flow rate adjustment pipe TB1 is configured using pipes with a smaller diameter than the pipe of line L8 used in the other configurations (configurations CP1 to CP4). Note that the configurations of configuration CP5 other than the flow rate adjustment pipe TB1 are the same as the other configurations. For example, the flow rate adjustment pipe TB1 is configured using pipes with a diameter approximately two-thirds the diameter of the pipe of line L8 used in the other configurations (configurations CP1 to CP4). For example, the pipes of line L6, line L7, line L8, and feedback line L9 are φ6 (6 mm diameter), and the flow rate adjustment pipe TB1 is φ4 (4 mm diameter). As a result, compared to the other configurations (configurations CP1 to CP4), the flow rate can be restricted by the flow rate adjustment pipe TB1 without using an orifice OR2. In this embodiment, the flow rate adjustment pipe TB1 has a smaller diameter than the pipes of, for example, the line L6, the line L7, the line L8, and the feedback line L9.

[0095] The flow rate adjustment pipe TB1 may constitute the entire line L8, or may constitute only a part of the line L8.

[0096] As described above, it is possible to configure the oxygen concentrator 1 as in configuration CP5.

[0097] As described above, the oxygen concentrator 1 can have, for example, the configuration CP1, the configuration CP2, the configuration CP3, the configuration CP4, or the configuration CP5.

[0098] In the above configuration examples, the solenoid valve V1 or the solenoid valve V2 is used to switch the connection, but a configuration other than the solenoid valve V1 or the solenoid valve V2 may be used. That is, the solenoid valve V1 or the solenoid valve V2 in the above examples is a "switching unit" capable of switching, and the specific configuration is not limited thereto. For example, the switching unit is not limited to a solenoid valve, and components such as an electric valve, a pneumatic valve, or a hydraulic valve can also be used. Note that it is preferable to use a solenoid valve as the switching unit because it switches quickly and the time required for switching is easy to control. Note that, similarly in the first embodiment, a solenoid valve can be used as the switching unit, and is not limited to a solenoid valve.

[0099] In addition, in the above configuration examples, an orifice OR2 and a flow rate adjustment pipe TB1 are provided between the check valves 17A and 17B and the air chamber 12. The orifice OR2 and the flow rate adjustment pipe TB1 both have the function of adjusting the flow rate. In particular, the orifice OR2 and the flow rate adjustment pipe TB1 have the function of restricting the flow rate. In this way, the orifice OR2 and the flow rate adjustment pipe TB1 function as a flow rate adjustment unit (or flow rate restriction unit) capable of adjusting the flow rate. Therefore, the specific configuration of the flow rate adjustment unit capable of adjusting the flow rate is not limited to an orifice or pipe, and other components can also be used as the flow rate adjustment unit. For example, a needle valve (adjustment valve) can also be used as the flow rate adjustment unit. Note that the specific configuration of orifices other than the orifice OR2, such as the orifice OR1, provided in the feedback line L9 as flow rate adjustment units capable of adjusting the flow rate is not limited to an orifice. In other words, the specific configuration of the orifices shown in FIG. 7 and the like is not limited to an orifice, and other components can also be used as the flow rate adjustment unit. For example, the orifice OR1 is a first flow rate adjustment unit, and the orifice OR2 is a second flow rate adjustment unit. It is preferable that an orifice be used as each of the first flow rate adjustment unit and the second flow rate adjustment unit from the viewpoint of cost and ease of installation. Similarly, in the first embodiment, an orifice can be used as the flow rate adjustment unit, and is not limited to an orifice.

[0100] <Comparison of each configuration> Next, a comparison of each configuration of the oxygen concentrator 1 will be described. The comparison results (experimental results) of the oxygen concentrator 1 with each configuration will be described below as Comparison Result C1, Comparison Result C2, Comparison Result C3, Comparison Result C4, and Comparison Result C5. Note that a digital flow meter was used for the "flow rate" in this embodiment. The flow meter is, for example, a flow meter manufactured by SMC (PFM710-C6-C, measurement range: 0.2 to 10 L / min, maximum pressure: 0.75 MPa).

[0101] (Comparison result C1) First, comparison result C1 will be described. Comparison result C1 is a comparison result of the fluctuation of oxygen concentration depending on whether or not orifice OR2 is present. FIG. 12 is a diagram showing an example of comparison result C1. FIG. 12 shows the comparison result, with configuration CP3 representing a representative example when orifice OR2 is present and configuration CP4 representing a representative example when orifice OR2 is not present. FIG. 12 shows the difference (%) in oxygen concentration (%) of the oxygen-enriched gas discharged when oxygen concentrators 1 of each configuration are operated for a predetermined time (e.g., two hours or more). The difference in oxygen concentration is the difference between the maximum and minimum values of the fluctuating oxygen concentration. FIG. 12 also shows the difference in oxygen concentration corresponding to the flow rate of the discharged oxygen-enriched gas when the flow rate is 1.5 L / min, 2.0 L / min, 2.5 L / min, and 3.0 L / min.

[0102] As shown in Figure 12, the difference in oxygen concentration is smaller in configuration CP3 than in configuration CP4 at any flow rate. That is, the presence of orifice OR2 can suppress fluctuations in oxygen concentration more than the absence of orifice OR2. In other words, by providing orifice OR2 in oxygen concentrator 1, fluctuations in oxygen concentration can be suppressed and the oxygen concentration can be stabilized.

[0103] Moreover, Fig. 13 is a diagram showing maximum values of oxygen concentration corresponding to Fig. 12. Fig. 14 is a diagram showing minimum values of oxygen concentration corresponding to Fig. 12. That is, Fig. 13 and Fig. 14 show the results of comparison between configurations CP3 and CP4, similar to Fig. 12.

[0104] As shown in Figures 13 and 14, the configuration CP3 tends to have a higher oxygen concentration than the configuration CP4. Note that the configuration CP3 tends to have a higher oxygen concentration in both the maximum and minimum oxygen concentrations. In other words, the presence of the orifice OR2 allows for a higher oxygen concentration than the absence of the orifice OR2. In other words, providing the orifice OR2 in the oxygen concentrator 1 allows for a higher oxygen concentration.

[0105] 12, 13, and 14 showing the comparison result C1, by providing the orifice OR2 in the oxygen concentrator 1, the oxygen concentration can be stabilized and increased.

[0106] (Comparison result C2) Next, comparison result C2 will be described. Comparison result C2 is a comparison result of the variation in oxygen concentration depending on the position of orifice OR2. FIG. 15 is a diagram showing an example of comparison result C2. FIG. 15 shows the comparison results for configurations CP1, CP2, and CP3. FIG. 15 shows the difference (%) in oxygen concentration (%) of the oxygen-enriched gas discharged when the oxygen concentrator 1 of each configuration is operated for a predetermined time. The difference in oxygen concentration is the difference between the maximum and minimum values of the fluctuating oxygen concentration. FIG. 15 also shows the difference in oxygen concentration corresponding to each flow rate of the discharged oxygen-enriched gas when the flow rate is 1.5 L / min, 2.0 L / min, 2.5 L / min, and 3.0 L / min.

[0107] 15, at any flow rate, the difference in oxygen concentration is smaller in configuration CP1 than in configurations CP2 and CP3. That is, by providing orifice OR2 immediately after check valve 17A or check valve 17B as in configuration CP1, fluctuations in oxygen concentration can be minimized. That is, by providing orifice OR2 immediately after check valve 17A or check valve 17B in oxygen concentrator 1, the oxygen concentration can be effectively stabilized.

[0108] In this way, it is possible to stabilize the oxygen concentration by providing the orifice OR2 (comparison result C1), but the oxygen concentration can be most effectively stabilized by providing the orifice OR2 immediately after the check valve 17A or the check valve 17B (comparison result C2).

[0109] (Comparison result C3) Next, comparison result C3 will be described. Comparison result C3 is a comparison result of the fluctuation of oxygen concentration due to the orifice OR2 and the flow rate adjustment pipe TB1. FIG. 16 is a diagram showing an example of comparison result C3. FIG. 16 shows the comparison result with a representative example when the orifice OR2 is present as configuration CP3, a representative example when the orifice OR2 is not present as configuration CP4, and a representative example when the flow rate adjustment pipe TB1 is present as configuration CP5. FIG. 16 shows the comparison result when the oxygen concentrator 1 of each configuration is operated for a predetermined time and the difference (%) in oxygen concentration of the oxygen-enriched gas discharged. The difference in oxygen concentration is the difference between the maximum and minimum values of the fluctuating oxygen concentration. FIG. 16 also shows the difference in oxygen concentration corresponding to the flow rate of the discharged oxygen-enriched gas when the flow rate is 1.5 L / min, 2.0 L / min, 2.5 L / min, and 3.0 L / min.

[0110] As shown in Figure 16, the difference in oxygen concentration is smaller for configurations CP3 and CP5 than for configuration CP4 at any flow rate. That is, when the orifice OR2 is provided or when the flow rate adjustment pipe TB1 is provided, fluctuations in oxygen concentration can be suppressed more than when the orifice OR2 is not provided. In other words, by providing the orifice OR2 or the flow rate adjustment pipe TB1 in the oxygen concentrator 1, the oxygen concentration can be stabilized. Furthermore, when the flow rate adjustment pipe TB1 is provided, the oxygen concentration can be stabilized to the same extent as when the orifice OR2 is provided.

[0111] In this way, the stabilization of the oxygen concentration occurs not only when the orifice OR2 is provided (comparison results C1 and C2), but also when the flow rate adjustment pipe TB1 is provided (comparison result C3).

[0112] It is expected that the flow rate regulation effect can be enhanced by designing the flow rate regulation pipe TB1 to have a long pipe length, and therefore the flow rate regulation pipe TB1 may be designed to have a long pipe length.

[0113] (Comparison result C4) Next, comparison result C4 will be described. Comparison result C4 is a comparison result of the fluctuation of oxygen concentration over time for each configuration. FIG. 17 is a diagram showing an example of comparison result C4. FIG. 17 shows the comparison results for configurations CP1, CP2, CP3, CP4, and CP5. FIG. 17 shows the oxygen concentration (%) of the oxygen-enriched gas discharged from the oxygen concentrator 1 of each configuration. FIG. 17 shows the fluctuation corresponding to configuration CP1 as line H1, the fluctuation corresponding to configuration CP2 as line H2, the fluctuation corresponding to configuration CP3 as line H3, the fluctuation corresponding to configuration CP4 as line H4, and the fluctuation corresponding to configuration CP5 as line H5. FIG. 17 also shows each fluctuation over a 60-minute period. In FIG. 17, the flow rate of the discharged oxygen-enriched gas was constant at 2.0 L / min.

[0114] As shown in Figure 17, the oxygen concentration was roughly equal and high for configurations CP1 and CP3. At a flow rate of 2.0 l / min in particular, configuration CP1 tended to have a higher oxygen concentration than configuration CP3. The oxygen concentration decreased in the order of configurations CP2, CP5, and CP4. In other words, by providing the orifice OR2 and flow rate adjustment pipe TB1, the oxygen concentration could be increased compared to when they were not provided (configuration 4).

[0115] 17, the fluctuation of the oxygen concentration over time is small for configurations CP1 and CP3. That is, configurations CP1 and CP3 are particularly effective in stabilizing the oxygen concentration. Furthermore, configurations CP2 and CP5 have a larger fluctuation range of the oxygen concentration than configurations CP1 and CP3, but are more effective in stabilizing the oxygen concentration than configuration CP4.

[0116] In this way, providing the orifice OR2 can reduce the fluctuation range of the oxygen concentration, and providing the orifice OR2 at the positions of the components CP1 and CP3 can effectively stabilize the oxygen concentration. Furthermore, the components CP1 and CP3 maintain a roughly constant oxygen concentration over time, and the stability of the oxygen concentration is high.

[0117] (Comparison results) According to the above comparison results C1 to C4, the oxygen concentration can be stabilized more effectively when the orifice OR2 is provided (configuration CP1, configuration CP2, configuration CP3) than when the orifice OR2 is not provided (configuration CP4). Furthermore, the oxygen concentration can be increased more effectively when the orifice OR2 is provided (configuration CP1, configuration CP2, configuration CP3) than when the orifice OR2 is not provided (configuration CP4). In particular, configurations CP1 and CP3 can effectively stabilize the oxygen concentration and can also effectively increase the oxygen concentration.

[0118] Furthermore, in the configurations CP1 and CP3, the oxygen concentration is maintained roughly constant over time, and the effect of stabilizing the oxygen concentration over time is high.

[0119] Furthermore, even when a flow rate adjustment pipe TB1 is provided instead of an orifice OR2 (configuration CP5), the oxygen concentration can be stabilized and increased compared to when an orifice OR2 is not provided (configuration CP4).

[0120] The oxygen concentrator 1 preferably exhibits minimal fluctuations in oxygen concentration. For this reason, the configurations CP1, CP2, and CP3 are preferred for the oxygen concentrator 1, with configurations CP1 and CP3 being particularly preferred. Furthermore, when the oxygen concentrator 1 is used to generate ozone, for example, large capacity, high concentration, and stability are required, with a particularly high oxygen concentration being particularly preferred. Therefore, when the oxygen concentrator 1 is used to generate ozone, the configurations CP1, CP2, and CP3 are preferred, with configurations CP1 and CP3 being particularly preferred. Furthermore, the configurations CP1, CP2, CP3, and CP5 can stabilize and increase the oxygen concentration compared to the configuration CP4, which does not include an orifice OR2 or the like. Therefore, the configurations CP1, CP2, CP3, and CP5 can be expected to achieve large capacity while achieving effects such as stabilization of oxygen concentration. Furthermore, when the oxygen concentrator 1 is used for medical purposes, stability of the oxygen concentration is particularly required. Therefore, the configurations CP1 and CP3 are particularly preferred when the oxygen concentrator 1 is used for medical purposes.

[0121] <Processing flow> FIG. 18 is a timing chart (time chart) showing an example of the operation flow of the oxygen concentrator 1 according to this embodiment. The timing chart in FIG. 18 is a more detailed version of the timing chart in FIG. 4. FIG. 18 shows the operation of each component in chronological order. FIG. 18 shows the states of the solenoid valve V1, the solenoid valve V2, the second adsorption unit 8B, the first adsorption unit 8A, the solenoid valve V3, and the compressor 5. Regarding the state of the compressor 5, the introduction (suction) of outside air via line L1 is indicated as "outside air introduction," and the suction from the first adsorption unit 8A or the second adsorption unit 8B via circulation line L10 is indicated as "zeolite suction." Periods K1 to K8 are executed sequentially, and the operation is repeated, with periods K1 to K8 forming one cycle. The switching times of the solenoid valve V1 and the solenoid valve V2 during periods K1 to K8 are approximately several tens of seconds. In particular, the pressure equalization times during periods K4 and K8 are approximately 0.5 to 3 seconds. The switching time can be adjusted depending on the conditions of the device, etc. Note that Fig. 18 shows a timing chart during operation, and period K1 does not represent the state immediately after the oxygen concentrator 1 is started.

[0122] During period K1, solenoid valve V1 is in the connected state S1, and solenoid valve V2 selects port NO (port NO and port COM are connected). As a result, second adsorption unit 8B is pressurized and functions as an adsorption unit that adsorbs nitrogen and moisture. In addition, gas (which can also be considered dry gas or concentrated oxygen) that has passed through second adsorption unit 8B passes through check valve 17B and line L8 and is stored in air chamber 12. The gas stored in air chamber 12 is discharged through regulator 24.

[0123] Meanwhile, a portion of the gas discharged from the second adsorption unit 8B flows into the first adsorption unit 8A via the feedback line L9. Furthermore, because the first adsorption unit 8A is depressurized during period K8, the nitrogen and moisture adsorbed in the first adsorption unit 8A are released and are discharged from the first adsorption unit 8A together with the gas (oxygen) that has flowed in from the second adsorption unit 8B. The gas (containing a large amount of nitrogen and moisture) discharged from the first adsorption unit 8A and flowing into the circulation line L10 is blocked by the solenoid valve V2, but is released to the outside of the system through the check valve 21 connected to the line L12. In particular, when the solenoid valve V1 is switched, most of the nitrogen and moisture are discharged through the check valve 21.

[0124] During period K2, solenoid valve V2 selects port NC (port NC and port COM are connected). The second adsorption unit 8B remains pressurized. During period K1, a portion of the gas discharged from the second adsorption unit 8B passes through feedback line L9 and the first adsorption unit 8A and is blocked by solenoid valve V2, causing the pressure in the first adsorption unit 8A to increase to a certain level. However, since check valve 21 is connected to line L12, the gas is discharged when the pressure on the primary side of check valve 21 exceeds the pressure on the secondary side of check valve 21. At this time, most of the nitrogen and moisture released from the first adsorption unit 8A are discharged. Furthermore, when period K2 begins, solenoid valve V2 switches from port NO to port NC, the blocked gas flows to compressor 5, causing the pressure in the system to decrease. This creates a vacuum in the first adsorption unit 8A, ensuring more reliable discharge of nitrogen and moisture. The first adsorption section 8A and the second adsorption section 8B are separated by the orifice OR1, resulting in different pressure fluctuations. In particular, when solenoid valve V2 switches from port NO to port NC, the blocked gas flows to compressor 5, causing a drop in pressure in the first adsorption section 8A. Meanwhile, the presence of orifice OR1 facilitates maintaining a high pressure in the second adsorption section 8B. As the pressure in the first adsorption section 8A drops, the nitrogen and moisture adsorbed by the first adsorption section 8A are released from the first adsorption section 8A (first regeneration). When solenoid valve V2 switches and connects ports NC and COM, the adsorption column is placed in a vacuum state, ensuring the moisture is released and extending the life of the adsorbent. At this time, check valve 21 prevents the introduction of outside air from the outside, ensuring the vacuum is maintained. The circulation line L10 also includes a line L12 for releasing nitrogen and moisture, which is equipped with a check valve 21 for discharging the gas (containing a large amount of nitrogen and moisture). During the period K2, even if the compressor 5 is sucking air, outside air is not introduced from the secondary side of the check valve 21, so that the compressor 5 is effectively sucking air.

[0125] Furthermore, the gas discharged from the second adsorption unit 8B flows into the first adsorption unit 8A via feedback line L9, flows from the first adsorption unit 8A through circulation line L10 to the compressor 5, and then circulates to the second adsorption unit 8B. As the gas flows through the first adsorption unit 8A, nitrogen and moisture are discharged from the first adsorption unit 8A (second regeneration). In particular, as the gas in the first adsorption unit 8A is sucked by the compressor 5, most of the moisture remaining in the adsorbent is removed. Furthermore, when gas is circulated within the system by the suction of the compressor 5, the compressor 5 sucks in oxygen with a higher concentration than normal air, and therefore the oxygen concentration of the gas discharged from the compressor 5 also increases, and the oxygen concentration of the gas discharged from the regulator 24 also increases.

[0126] During period K2, the gas discharged from the second adsorption section 8B flows through the check valve 17B and line L8 to the air chamber 12 and is discharged from the regulator 24, so the pressure continues to drop unless gas is supplied.

[0127] Then, as the pressure in the first adsorption section 8A decreases, the gas discharged from the second adsorption section 8B flows in, and nitrogen and moisture are further discharged (third regeneration).

[0128] During period K3, solenoid valve V2 selects port NO (port NO and port COM are connected). The second adsorption unit 8B is maintained in a pressurized state. During period K3, the gas discharged from the second adsorption unit 8B passes through feedback line L9 and first adsorption unit 8A, while being blocked by solenoid valve V2. As the gas discharged from the second adsorption unit 8B passes through first adsorption unit 8A, the nitrogen and moisture remaining in first adsorption unit 8A are removed and the gas is discharged into circulation line L10. As a result, the pressure in circulation line L10 becomes high. When the pressure in circulation line L10 increases, the gas (including the remaining nitrogen and moisture) that has accumulated in circulation line L10 is released from check valve 21 to the outside of the system (fourth regeneration).

[0129] During period K4, solenoid valve V1 is in the connected state S2. In this state, pressurized gas is no longer supplied to second adsorption unit 8B, but gas that has passed through second adsorption unit 8B is discharged through line L8, air chamber 12, and regulator 24. Note that as long as the pressure on the primary side of check valve 17B remains high, gas that has passed through second adsorption unit 8B is discharged via the air chamber 12, etc.

[0130] Gas also flows from the second adsorption unit 8B to the first adsorption unit 8A via feedback line L9, and then returns to the second adsorption unit 8B via solenoid valve V1. While the pressure decreases along this path, the first adsorption unit 8A and the second adsorption unit 8B are connected to each other via solenoid valve V1, and the pressures in the first adsorption unit 8A and the second adsorption unit 8B approach equalization (pressure equalization). In particular, during period K4 (or period K8), the pressures in the first adsorption unit 8A and the second adsorption unit 8B are released, releasing nitrogen and moisture. Prior to the transition to connected state S2, the pressure in the first adsorption unit 8A, which was in the regeneration process, was low, while the pressure in the second adsorption unit 8B, which was in the adsorption process, was high. Therefore, the time required for period K4 (e.g., approximately 0.5 to 3 seconds) is ensured to equalize the pressures in both units to some extent. Thus, period K4 is a period for reducing the pressure difference between the first adsorption section 8A and the second adsorption section 8B, allowing for smooth pressurization of the first adsorption section 8A and exhaust (regeneration) of the second adsorption section 8B in the next step. Furthermore, the pressure difference between the primary and secondary sides of each check valve 17A and 17B is small, making backflow more likely. However, the orifice OR2 prevents the secondary pressure from decreasing, suppressing backflow. Note that the introduction of outside air is blocked by the solenoid valve V1, causing the pressure within the system to decrease. The pressure in the air chamber 12 decreases, but the capacity of the air chamber 12 and the capacity of the compressor 5 are pre-selected to take this decrease into account. Additionally, a certain level of pressure (pressure in the air chamber 12) can be maintained by extending the switching time of the solenoid valve V1.

[0131] During period K4, the amount of gas flowing into the air chamber 12 can be controlled by equalizing the pressures in the first adsorption section 8A and the second adsorption section 8B. If equalization during period K4 is not performed, the pressure difference between the first adsorption section 8A and the second adsorption section 8B remains large, potentially resulting in malfunction. For example, if the connection state of the solenoid valve V1 is switched directly from connection state S1 to connection state S3 without equalization, pressurized gas is supplied to the first adsorption section 8A. However, it takes time for the pressure in the first adsorption section 8A to change from a low state to a high state, and the discharge of oxygen-enriched gas from the regulator 24 may decrease until the pressure increases. In contrast, by having connection state S2 between the connection state of the solenoid valve V1 switching from connection state S1 to connection state S3, the pressure in the first adsorption section 8A can be increased to a certain level during connection state S2. Switching to connection state S3 in this state shortens the time it takes for the pressure in the first adsorption section 8A to increase, thereby suppressing the decrease in the discharge of oxygen-enriched gas from the regulator 24.

[0132] Furthermore, equalizing the connection state S2 can also suppress noise during gas release, etc. For example, if the connection state of the solenoid valve V1 is directly switched from the connection state S1 to the connection state S3 without equalization, the second adsorption unit 8B, which is in a high-pressure state, suddenly enters the regeneration process, is connected to the circulation line L10, and gas flows through the circulation line L10. If the gas is blocked by the solenoid valve V2, the pressure in the circulation line L10 increases, and gas is released through the check valve 21. If the pressure in the circulation line L10 is too high, the gas release force may be strong, which may cause noise. In contrast, by providing the connection state S2 between the connection state S1 and the connection state S3, the pressure in the second adsorption unit 8B, which was in a high-pressure state during the adsorption process during the connection state S2, decreases. Then, when the connection state is switched to the connection state S3 in this state, the pressure in the circulation line L10 is prevented from becoming too high, the gas release force from the check valve 21 is suppressed, and noise is suppressed.

[0133] During period K5, solenoid valve V1 is in the connected state S3. As a result, the pressurized gas discharged from compressor 5 flows into first adsorption section 8A, pressurizing first adsorption section 8A. Then, first adsorption section 8A functions as an adsorption section that adsorbs nitrogen and moisture from the pressurized gas. Gas that passes through first adsorption section 8A passes through check valve 17A and line L8 and is stored in air chamber 12. The gas stored in air chamber 12 is discharged through regulator 24.

[0134] Furthermore, a portion of the gas discharged from the first adsorption unit 8A flows into the second adsorption unit 8B via the feedback line L9. Because the second adsorption unit 8B is not pressurized at the time (immediately after) the solenoid valve V1 is switched to the connection state S3, the nitrogen and moisture adsorbed during the period K1 to K3 are released from the second adsorption unit 8B and discharged together with the gas flowing in from the first adsorption unit 8A.

[0135] The gas (containing a large amount of nitrogen and moisture) discharged from the second adsorption section 8B and flowing into the circulation line L10 is blocked by the solenoid valve V2, but is released to the outside of the system through the check valve 21 connected to the line L12.

[0136] During period K6, solenoid valve V2 selects port NC (port NC and port COM are connected). While first adsorption unit 8A functions as an adsorption unit, the gas that was blocked by solenoid valve V2 flows to compressor 5. As a result, the pressure in second adsorption unit 8B, circulation line L10, and the path of solenoid valve V2 decreases. Gas flows from first adsorption unit 8A into second adsorption unit 8B, and nitrogen and moisture are released.

[0137] During period K7, solenoid valve V2 selects port NO (port NO and port COM are connected). While first adsorption unit 8A functions as an adsorption unit, the gas (containing nitrogen and moisture) discharged from second adsorption unit 8B and flowing to circulation line L10 is blocked by solenoid valve V2 but is released to the outside of the system through check valve 21 connected to line L12. This allows as much nitrogen and moisture as possible to be released to the outside of the system.

[0138] During the period K8, the solenoid valve V1 is in the connected state S2, i.e., the operation during the period K8 is the same as that during the period K4.

[0139] In this manner, the period from K1 to K8 is carried out, and the first adsorption unit 8A and the second adsorption unit 8B alternately perform adsorption and regeneration (swing), thereby producing oxygen-enriched gas. Then, the period from K1 to K8 is carried out again, and the same operation is repeatedly carried out. Also, by opening the solenoid valve V3, water can be drained from the water drain tank 6, and this is done, for example, at the timing of the period K3. Note that the timing at which the solenoid valve V3 is opened may be set, for example, at regular intervals, and is not limited to the period K3.

[0140] <Action and effect> As described above, in this embodiment, the oxygen concentrator 1 includes a line L1 as a first line, a compressor 5 that draws in and pressurizes gas via the line L1, a solenoid valve V1 as a switching unit to which the pressurized gas discharged from the compressor 5 is supplied and which switches the supply destination of the pressurized gas, a first adsorption unit 8A to which the pressurized gas is supplied from one end side by the solenoid valve V1 and which adsorbs nitrogen and moisture from the pressurized gas, a second adsorption unit 8B to which the pressurized gas is supplied from one end side by the solenoid valve V1 and which adsorbs nitrogen and moisture from the pressurized gas, a check valve 17A provided at the other end side of the first adsorption unit 8A and which has the first adsorption unit 8A side as a first check valve with the first adsorption unit 8A side as a primary side, and a check valve 17B provided at the other end side of the second adsorption unit 8B and which has the second adsorption unit 8B side as a secondary check valve. the check valve 17B as a second check valve with the arrival portion 8B side as its primary side; a feedback line L9 connecting the first adsorption portion 8A and the check valve 17A and the second adsorption portion 8B and the check valve 17B; a control device 13 that controls the solenoid valve V1 to supply pressurized gas to either the first adsorption portion 8A or the second adsorption portion 8B and to supply oxygen-enriched gas discharged from that adsorption portion to the other of the first adsorption portion 8A or the second adsorption portion 8B via the feedback line L9; an orifice OR1 as a first flow rate adjustment portion provided in the feedback line L9; and an orifice OR2 as a second flow rate adjustment portion provided on the secondary side of the check valve 17A and the check valve 17B.

[0141] According to this configuration, the orifice OR2 (second flow rate adjustment unit) can suppress fluctuations in the pressure difference between the primary side and secondary side of the check valve 17A or the check valve 17B. This suppresses backflow in the check valve 17A or the check valve 17B, and suppresses a decrease in the amount of oxygen-enriched gas produced. That is, the discharge amount of oxygen-enriched gas can be stabilized. Furthermore, because backflow is suppressed, it is possible to increase the discharge amount of oxygen-enriched gas. Furthermore, by providing the orifice OR2 as the second flow rate adjustment unit on the secondary side of the check valve 17A or the check valve 17B, the oxygen concentration can be stabilized and increased. That is, the oxygen concentrator 1 can be used for a variety of purposes.

[0142] In this embodiment, each of the first flow rate adjustment unit and the second flow rate adjustment unit is an orifice.

[0143] This configuration can reduce costs and improve ease of installation.

[0144] In addition, in this embodiment, the secondary lines (line L6, line L7, line L8) of check valve 17A and check valve 17B are connected to air chamber 12, and orifice OR2 is provided between check valve 17A and check valve 17B and air chamber 12.

[0145] This configuration can suppress backflow at check valve 17A and check valve 17B, and can suppress a decrease in the amount of oxygen-enriched gas produced. Also, the oxygen concentration can be stabilized and increased.

[0146] In this embodiment, the orifice OR2 is provided between the check valves 17A and 17B and the air chamber 12, and closer to the check valves 17A and 17B than to the air chamber 12.

[0147] According to this configuration, the oxygen concentration can be stabilized and increased, and the oxygen concentration can be stabilized over time.

[0148] In addition, in this embodiment, the line is connected to the air chamber 12 by joining the secondary side of the check valve 17A and the secondary side of the check valve 17B at a joining point, and the orifice OR2 is provided between the secondary side of the check valve 17A and the secondary side of the check valve 17B and the joining point, on each of the secondary sides of the check valve 17A and the secondary side of the check valve 17B.

[0149] This configuration allows orifices OR2 to be provided near check valves 17A and 17B. This effectively stabilizes and increases the oxygen concentration. Furthermore, the oxygen concentration can be stabilized over time.

[0150] In this embodiment, the orifice OR2 is connected to each of the check valve 17A and the check valve 17B.

[0151] With this configuration, the orifice OR2 can be provided particularly close to each of the check valves 17A and 17B. This means that the oxygen concentration can be effectively stabilized and increased. Furthermore, the oxygen concentration can be stabilized over time. Furthermore, the orifice OR2 can be installed at the end of a pipe or a junction, making installation easier.

[0152] In this embodiment, the orifice OR2 is provided between the check valves 17A and 17B and the air chamber 12, and at a position closer to the air chamber 12 than the check valves 17A and 17B.

[0153] This configuration allows the orifice OR2 to be provided near the air chamber 12. This means that the oxygen concentration can be effectively stabilized and increased. Furthermore, the oxygen concentration can be stabilized over time.

[0154] In addition, in this embodiment, the line is connected to the air chamber 12 by joining the secondary side of the check valve 17A and the secondary side of the check valve 17B at a joining point, and the orifice OR2 is provided between the air chamber 12 and the joining point.

[0155] According to this configuration, the oxygen concentration can be stabilized and increased, and furthermore, the oxygen concentration can be stabilized over time.

[0156] In this embodiment, the orifice OR2 is provided between the air chamber 12 and the junction, and closer to the air chamber 12 than the junction.

[0157] This configuration allows the orifice OR2 to be provided near the air chamber 12. This means that the oxygen concentration can be effectively stabilized and increased. Furthermore, the oxygen concentration can be stabilized over time.

[0158] In this embodiment, the orifice OR2 is connected to the air chamber 12.

[0159] This configuration allows the orifice OR2 to be located particularly close to the air chamber 12. This means that the oxygen concentration can be effectively stabilized and increased. It also allows the oxygen concentration to be stabilized over time. Furthermore, the orifice OR2 can be installed at the end of a pipe, etc., making installation easier.

[0160] In addition, in this embodiment, the line is connected to the air chamber 12 by joining the secondary side of the check valve 17A and the secondary side of the check valve 17B at a joining point, and the orifice OR2 is provided between the joining point and the air chamber 12, at a position closer to the joining point than the air chamber 12.

[0161] This configuration allows the orifice OR2 to be provided near the confluence, which means that the oxygen concentration can be stabilized and increased.

[0162] In this embodiment, the orifice OR2 is connected to a junction member 41 that forms a junction point.

[0163] This configuration allows the orifice OR2 to be located particularly close to the confluence, which in turn stabilizes and increases the oxygen concentration. Furthermore, the orifice OR2 can be easily installed.

[0164] <<Variations>> The present invention is not limited to the above-described embodiments. In other words, designs that are produced by those skilled in the art with appropriate design modifications to the above-described specific examples are also included within the scope of the present invention as long as they include the features of the present invention. Furthermore, the elements of the above-described embodiments and the following modifications can be combined to the extent technically possible, and such combinations are also included within the scope of the present invention as long as they include the features of the present invention.

[0165] For example, in the above embodiment, a case where a relief type regulator is used as the regulator 24 has been described as an example, but the specifications of the regulator 24 are not limited, and for example, a non-relief type regulator may be used.

[0166] In the above embodiment, the solenoid valve V2 is switched from a state in which the line L2 and the circulation line L10 are connected to a state in which the line L2 and the line L1 are connected during the period in which the pressurized gas is being supplied to the solenoid valve V2. However, the solenoid valve V2 may be controlled to switch from a state in which the line L2 and the line L1 are connected to a state in which the line L2 and the circulation line L10 are connected during the period in question. That is, the solenoid valve V2 may select port NO during period T2 within period T1, and may select port NC during period T3 within period T1.

[0167] Furthermore, in the above embodiment, a case where check valves are provided at various locations is taken as an example, but solenoid valves may be provided instead of the check valves.

[0168] In addition, in the above embodiment, the orifice diameter of the orifice OR2 is described as being larger than orifice diameter of the orifice OR1, but the relationship between the orifice diameters is not limited to the above, depending on factors such as the balance with the amount of oxygen-enriched gas supplied to the air chamber 12.

[0169] In the above embodiment, the orifice OR2 is provided immediately after the check valves 17A and 17B in the configuration CP1, but this is not limited to this. That is, the specific location of the orifice OR2 is not limited as long as it is provided in a position closer to the check valves 17A and 17B than the air chamber 12.

[0170] In the above embodiment, the orifice OR2 is provided immediately after the junction in the configuration CP2, but this is not limited to this. That is, the specific location of the orifice OR2 is not limited as long as it is provided at a position closer to the junction than the air chamber 12.

[0171] In the above embodiment, the orifice OR2 is provided immediately before the air chamber 12 in the configuration CP3, but this is not limited to this. In other words, the specific location of the orifice OR2 is not limited as long as it is provided at a position closer to the air chamber 12 than the check valves 17A and 17B.

[0172] Furthermore, in the above embodiment, the case where the orifice OR2 is provided between the check valves 17A and 17B and the air chamber 12 has been described, but there is no limit to the number of orifices OR2 provided between the check valves 17A and 17B and the air chamber 12. For example, a plurality of orifices OR2 may be provided, such as by providing an orifice OR2 as in the configuration CP1 and another orifice OR2 as in the configuration CP3.

[0173] In the above embodiment, the orifice OR2 and the flow rate adjustment pipe TB1 are provided between the check valve 17A and the check valve 17B and the air chamber 12. The orifice OR2 and the flow rate adjustment pipe TB1 may be combined and disposed between the check valve 17A and the check valve 17B and the air chamber 12.

[0174] Furthermore, in the above embodiment, the case where the flow rate adjustment pipe TB1 is provided in the line L8 between the check valves 17A and 17B and the air chamber 12 has been described, but the installation position of the flow rate adjustment pipe TB1 is not limited. That is, the flow rate adjustment pipe TB1 may be provided at any position between the check valves 17A and 17B and the air chamber 12. For example, the flow rate adjustment pipe TB1 may be provided in place of the orifice OR2 provided in the configuration CP1, configuration CP2, or configuration CP3.

[0175] Furthermore, in the above embodiment, the oxygen concentrator 1 is configured to include the compressor 5, but the specific configuration of the pressurizing unit is not limited as long as it can draw in and pressurize gas. [Explanation of symbols]

[0176] 1: Oxygen concentrator 5: Compressor 8: Adsorption device 8A: First suction part 8B:Second suction part L9: Feedback line L10: Circulation line 13: Control device 17A: Check valve (first check valve) 17B: Check valve (second check valve) L1: Line (first line) V1: Solenoid valve (switching valve) OR1: Orifice (first flow rate adjustment part) OR2: Orifice (second flow rate adjustment part)

Claims

1. The first line and a compressor that draws in gas through the first line and pressurizes it; a switching unit to which the pressurized gas discharged from the compressor is supplied and which switches the supply destination of the pressurized gas; a first adsorption unit to which the pressurized gas is supplied from one end side by the switching unit and which adsorbs nitrogen and moisture from the pressurized gas; a second adsorption section to which the pressurized gas is supplied from one end side by the switching section and which adsorbs nitrogen and moisture from the pressurized gas; a first check valve provided on the other end side of the first adsorption unit, the first check valve having a primary side on the first adsorption unit side; a second check valve provided at the other end of the second adsorption unit, the second check valve having a primary side on the second adsorption unit side; a feedback line connecting the first adsorption unit and the first check valve and the second adsorption unit and the second check valve; a control device that controls the switching unit to supply the pressurized gas to one of the first adsorption unit and the second adsorption unit, and supplies the oxygen-enriched gas discharged from the adsorption unit to the other of the first adsorption unit and the second adsorption unit via the feedback line; a first flow rate adjusting unit provided in the feedback line; a second flow rate adjustment unit provided on the secondary side of the first check valve and the second check valve; An oxygen concentrator comprising:

2. Each of the first flow rate adjustment unit and the second flow rate adjustment unit is an orifice. The oxygen concentrator of claim 1 .

3. The orifice diameter of the second flow rate adjustment unit is equal to or larger than the orifice diameter of the first flow rate adjustment unit.

3. The oxygen concentrator of claim 2.

4. a ratio of an orifice diameter of the second flow rate control unit to an orifice diameter of the first flow rate control unit is greater than 1 and less than 2; The oxygen concentrator of claim 3.

5. a line on the secondary side of the first check valve and the second check valve is connected to an air chamber; the second flow rate adjusting unit is provided between the first check valve and the second check valve and the air chamber; 5. The oxygen concentrator according to claim 1.

6. the second flow rate adjustment unit is provided between the first check valve and the second check valve and the air chamber, and at a position closer to the first check valve and the second check valve than to the air chamber.

6. The oxygen concentrator of claim 5.

7. the line is connected to the air chamber by joining the secondary side of the first check valve and the secondary side of the second check valve at a joining point, The second flow rate adjustment unit is provided between the secondary side of the first check valve and the secondary side of the second check valve and the confluence point, and is provided on each of the secondary side of the first check valve and the secondary side of the second check valve.

7. The oxygen concentrator of claim 6.

8. The second flow rate adjustment unit is connected to each of the first check valve and the second check valve.

8. The oxygen concentrator of claim 7.

9. the second flow rate adjustment unit is provided between the first check valve, the second check valve, and the air chamber, and at a position closer to the air chamber than the first check valve and the second check valve.

6. The oxygen concentrator of claim 5.

10. the line is connected to the air chamber by joining the secondary side of the first check valve and the secondary side of the second check valve at a joining point, The second flow rate adjustment unit is provided between the air chamber and the confluence point.

10. The oxygen concentrator of claim 9.

11. the second flow rate adjustment unit is provided between the air chamber and the junction and at a position closer to the air chamber than the junction.

11. The oxygen concentrator of claim 10.

12. the second flow rate adjusting unit is connected to the air chamber; 12. The oxygen concentrator of claim 11.

13. the line is connected to the air chamber by joining the secondary side of the first check valve and the secondary side of the second check valve at a joining point, the second flow rate adjustment unit is provided between the confluence and the air chamber and closer to the confluence than the air chamber.

6. The oxygen concentrator of claim 5.

14. The second flow rate adjustment unit is connected to a confluence member that constitutes the confluence point.

14. The oxygen concentrator of claim 13.

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