Oxygen concentration device, control method, and control program

Abstract

Provided are: an oxygen concentrator capable of preventing a drop in pilot pressure in the supply flow path open / closed section or the exhaust gas flow path open / closed section, wherein at least one of the supply flow path open / closed section or the exhaust gas flow path open / closed section is a pilot-operated solenoid valve; a control method; and a control procedure. An oxygen concentrator is provided configured such that pressure is applied to an adsorption cylinder whose pressure has already decreased before a pressure equalization step, and thus pressure drop in both adsorption cylinders can be prevented during the pressure equalization step, thereby preventing a drop in pilot pressure in the supply flow path open / closed section or the exhaust gas flow path open / closed section, wherein at least one of the supply flow path open / closed section or the exhaust gas flow path open / closed section is a pilot-operated solenoid valve.

Description

Technical Field

[0001] This invention relates to an oxygen concentrator that separates and concentrates oxygen from air and supplies it to a user. More specifically, with regard to an oxygen concentrator in which a pilot-operated solenoid valve is used in at least one of a supply flow path opening / closing unit or an exhaust flow path opening / closing unit, this invention relates to an oxygen concentrator, control method, and control procedure capable of controlling the pressure in multiple adsorption cartridges to prevent a drop in pilot pressure (the discharge pressure of the pressurized air supply unit, the internal pressure of the concentrated oxygen gas tank, or the internal pressure of the adsorption cartridge). Background Technology

[0002] Oxygen therapy is commonly performed as a treatment for patients with respiratory illnesses such as asthma and chronic obstructive pulmonary disease (COPD), in which the patient inhales oxygen gas or oxygen-enriched gas. In recent years, home oxygen therapy (HOT), administered at the patient's home to improve quality of life (QOL), has become mainstream. In home oxygen therapy, an oxygen concentrator is used as the oxygen supply source to deliver oxygen gas to the patient; this concentrator condenses the oxygen contained in the air to produce oxygen gas and supplies the resulting oxygen gas.

[0003] As oxygen concentrators, pressure swing adsorption (PSA) oxygen concentrators and vacuum pressure swing adsorption (VPSA) or vacuum pressure swing adsorption (VSA) oxygen concentrators are widely used.

[0004] An oxygen concentrator has multiple adsorption cylinders filled with adsorbent that selectively adsorbs nitrogen gas. Each of the multiple adsorption cylinders repeats an adsorption and desorption step to produce concentrated oxygen gas, which is stored in a concentrated oxygen gas tank. The adsorption step involves drawing pressurized air into the adsorption cylinder and adsorbing nitrogen gas onto the adsorbent, thereby generating oxygen gas from the pressurized air. The resulting concentrated oxygen gas is then stored in the concentrated oxygen gas tank. The desorption step involves depressurizing the adsorption cylinder by exposing it to the atmosphere, thereby releasing the nitrogen gas adsorbed on the adsorbent during the adsorption step into the atmosphere. By alternating between the adsorption and desorption steps among the multiple adsorption cylinders, the oxygen concentrator can continuously produce concentrated oxygen gas.

[0005] Regarding the oxygen concentrator, the following recommendations have been made: In order to improve the desorption efficiency in the desorption step, during the adsorption step, the concentrated oxygen gas generated in the adsorption cylinder is returned from the end of the concentrated oxygen outlet side to the adsorption cylinder in the desorption step through the flushing valve as the flushing gas. Subsequently, in order to efficiently generate highly concentrated oxygen gas, the adsorption cylinder is depressurized to discharge nitrogen, and then connected to the adsorption cylinder via the pressure equalization valve in the pressurization step, and the pressure is equalized (PTL 1 and 2).

[0006] On the other hand, to suppress power consumption in oxygen concentrators, methods have been proposed such as controlling compressor speed to regulate air supply (PTL 2) and using pilot-operated solenoid valves (PTL 3). Since pilot-operated solenoid valves operate the main valve with a large pilot pressure and thus switch the valve, the power consumption required for valve switching can be reduced compared to conventional direct-acting solenoid valves, even for large effective flow path cross-sections. Furthermore, since flow rate losses can be reduced, this allows for a reduction in the compressor's discharge flow rate, thereby reducing the power consumption required to drive the compressor, which is the main power-consuming device in the oxygen concentrator, potentially leading to power savings within the concentrator.

[0007] [List of Citations]

[0008] [Patent Literature]

[0009] [PTL 1] Japanese Unexamined Patent Application Publication No. 2002-79030

[0010] [PTL 2] Japanese Unexamined Patent Application Publication No. 11-207128

[0011] [PTL 3] Japanese Unexamined Patent Application Publication No. 2006-62932 Summary of the Invention

[0012] [Technical Issues]

[0013] Pilot-operated solenoid valves require a pilot pressure for switching operations, and, for example, when the pilot pressure is provided by the discharge pressure of a pressurized air supply unit, the discharge pressure of the pressurized air supply unit must be equal to or higher than the minimum operating pressure of the pilot-operated solenoid valve. The pilot pressure can be supplied by the internal pressure of the concentrated oxygen gas tank, the internal pressure of the adsorption cylinder, etc., and the discharge pressure of the pressurized air supply unit. Therefore, the pilot pressure (the discharge pressure of the pressurized air supply unit, the internal pressure of the concentrated oxygen gas tank, or the internal pressure of the adsorption cylinder) must be equal to or higher than the minimum operating pressure of the pilot-operated solenoid valve.

[0014] However, when pressure equalization is achieved by connecting the pressure-reducing adsorption cylinder and the adsorption cylinder in the pressurization step via the pressure equalization valve, the cylinder pressure drops to the pressure at which the two adsorption cylinders are equalized. This also causes a drop in the discharge pressure of the pressurized air supply unit and the pressure in the concentrated oxygen gas tank. More specifically, since there is only a supply valve between the pressurized air supply unit and the adsorption cylinder, when the supply valve is open, the pressurized air supply unit and the adsorption cylinder are connected to each other, and the discharge pressure of the pressurized air supply unit will drop to the internal pressure of the adsorption cylinder.

[0015] Furthermore, in the operating oxygen concentrator, concentrated oxygen gas is always extracted from the concentrated oxygen gas tank at a predetermined flow rate. When the internal pressure of the adsorption cylinder is higher than the internal pressure of the concentrated oxygen gas tank, the gas automatically flows from the adsorption cylinder to the concentrated oxygen gas tank through a check valve set between the adsorption cylinder and the concentrated oxygen gas tank, thereby maintaining the internal pressure between the adsorption cylinder and the concentrated oxygen gas tank at the same level. When the pressure equalization causes the internal pressure of the adsorption cylinder to drop below the pressure in the concentrated oxygen gas tank, the airflow from the adsorption cylinder to the concentrated oxygen gas tank stops, and therefore the pressure in the concentrated oxygen gas tank drops due to the continuous extraction of concentrated oxygen gas at a predetermined flow rate, and further drops to the lower internal pressure of the adsorption cylinder.

[0016] Furthermore, this problem is particularly pronounced and has adverse effects under low flow rate operation: for example, although low flow rate operation allows for the suppression of power consumption by reducing the rotational speed of the pressurized air supply unit and decreasing the air supply according to the oxygen extraction flow rate, the rotational speed of the pressurized air supply unit cannot be reduced below the level required to maintain the minimum operating pressure of the pilot-operated solenoid valve or a higher operating pressure. In addition, because the rotational speed of the pressurized air supply unit cannot be reduced further, air is supplied in excess relative to the oxygen extraction flow rate, leading to excessive oxygen adsorption and another adverse effect of reduced oxygen concentration.

[0017] In view of the above, the object of the present invention is to solve the problem of maintaining a pilot pressure equal to or higher than the minimum operating pressure of a pilot-operated solenoid valve during the pressure equalization step by preventing a drop in pilot pressure (discharge pressure of the pressurized air supply unit, internal pressure of the concentrated oxygen gas tank, or internal pressure of the adsorption cylinder). Therefore, an oxygen concentrator, a control method, and a control program are provided, which enable control of the rotational speed of the pressurized air supply unit to suppress power consumption or prevent a decrease in oxygen concentration due to excessive oxygen adsorption.

[0018] [Solution to the problem]

[0019] Therefore, the present invention is an oxygen concentrator that can prevent pressure drop in the two cylinders during the pressure equalization step by pre-initiating pressurization in the already depressurized adsorption cylinder before the pressure equalization step, thereby equalizing the pressure from the cylinder pressure of the already depressurized adsorption cylinder (under which condition the cylinder pressure of the already depressurized adsorption cylinder increases), and thus prevent a drop in the pilot pressure supplied to the pilot solenoid valve, which is used in at least one of the supply flow path opening / closing unit or the exhaust flow path opening / closing unit, and includes the following embodiments.

[0020] An oxygen concentrator according to one aspect of an embodiment of the present invention includes:

[0021] Multiple adsorption cartridges filled with an adsorbent that preferentially adsorbs nitrogen rather than oxygen;

[0022] A pressurized air supply unit is used to supply pressurized air to the adsorption cylinder;

[0023] A supply flow path opening / closing unit is used to connect the pressurized air supply unit and each adsorption cylinder, and to open / close the gas flow path of the pressurized air;

[0024] The exhaust flow path opening / closing unit is used to open / close the gas flow path for discharging gas from each adsorption cell;

[0025] Concentrated oxygen gas cylinder, used to store concentrated oxygen gas produced by multiple adsorption cartridges; and

[0026] The flow path opening / closing unit connects the end of each adsorption cartridge on the concentrated oxygen gas outlet side, allowing a portion of the generated concentrated oxygen gas to pass through it.

[0027] A pilot-operated solenoid valve is used for at least one of a supply flow path opening / closing unit or an exhaust flow path opening / closing unit.

[0028] The oxygen concentrator includes a flow path opening / closing control unit for controlling the opening / closing of the supply flow path opening / closing unit, the exhaust flow path opening / closing unit, and the connecting flow path opening / closing unit.

[0029] The flow path opening / closing control unit performs control in each adsorption cartridge in such a way that the following steps are repeated in the listed order.

[0030] (a) Pressure adsorption step, in which nitrogen in pressurized air is adsorbed onto the adsorbent in the adsorption tube by supplying pressurized air, and unadsorbed oxygen is extracted from the end of the concentrated oxygen gas outlet side of the adsorption tube.

[0031] (b) Pressure equalization step, equalizing the pressure in multiple adsorption cylinders;

[0032] (c) Depressurization and desorption step: Depressurize the adsorption cylinder, desorb the adsorbed nitrogen, and discharge it into the outside air;

[0033] (d) Pre-pressurization step: Pre-pressurizing the already depressurized adsorption cylinder; and

[0034] (e) Pressure equalization step, equalizing the pressure in the plurality of adsorption cylinders, and

[0035] This allows for the execution of (a) pressure adsorption steps in one or a set of adsorption cartridges, and (c) depressurization desorption steps and (d) pre-pressurization steps in another or a different set of adsorption cartridges.

[0036] In an oxygen concentrator according to one aspect of an embodiment, the flow path opening / closing control unit preferably controls the exhaust flow path opening / closing unit from the adsorption cartridge during the pre-pressurization step (d) to a closed state.

[0037] In an oxygen concentrator according to one aspect of an embodiment, the flow path opening / closing control unit preferably controls all supply flow path opening / closing units of the plurality of adsorption cartridges to the open state during the pressure equalization steps (b) and (e).

[0038] In an oxygen concentrator according to one aspect of an embodiment, the flow path opening / closing control unit preferably controls, in the latter half of the depressurization desorption step (c), a portion of the concentrated oxygen gas generated in the adsorption cartridge during pressurized adsorption to be flushed into the adsorption cartridge during depressurization desorption.

[0039] In an oxygen concentrator according to one aspect of the embodiment, the flow path opening / closing control unit preferably controls the connecting flow path opening / closing unit to a closed state during the depressurization and desorption step (c).

[0040] In an oxygen concentrator according to one aspect of the embodiment, the flow path opening / closing control unit can control the connecting flow path opening / closing unit to a closed state during the pressure equalization steps (b) and (e).

[0041] A method for controlling an oxygen concentrator according to one aspect of an embodiment.

[0042] This is used to control the pressure in multiple adsorption cylinders to prevent a drop in the pilot pressure supplied to a pilot-operated solenoid valve, which is used in at least one of a supply flow path opening / closing unit or an exhaust flow path opening / closing unit.

[0043] In each adsorption chamber, control is implemented in such a manner that the following steps are repeated in the listed order.

[0044] The pressurized adsorption step involves supplying pressurized air from the pressurized air supply unit to the adsorption cylinder, adsorbing nitrogen from the pressurized air onto the adsorbent in the adsorption cylinder, and extracting unadsorbed oxygen from the end of the concentrated oxygen gas outlet side of the adsorption cylinder.

[0045] The pressure equalization step equalizes the pressure in the multiple adsorption cylinders;

[0046] The decompression desorption step involves depressurizing the adsorption cylinder, desorbing the adsorbed nitrogen gas, and discharging it into the outside air.

[0047] The pre-pressurization step involves pre-pressurizing the already depressurized adsorption cylinder; and

[0048] The pressure equalization step equalizes the pressure in the multiple adsorption cylinders, and

[0049] This allows for the execution of a depressurization desorption step and a pre-pressurization step in another adsorption cell or another set of adsorption cells while a pressurization adsorption step is performed in one or more adsorption cells.

[0050] Control program of an oxygen concentrator according to one aspect of the embodiment

[0051] This is used to control the pressure in multiple adsorption cylinders to prevent a drop in the pilot pressure supplied to a pilot-operated solenoid valve, which is used in at least one of a supply flow path opening / closing unit or an exhaust flow path opening / closing unit.

[0052] The process of repeating the following steps in the listed order is performed in each adsorption tube.

[0053] The process of supplying pressurized air from the pressurized air supply unit to the adsorbent in the adsorption cylinder to adsorb nitrogen in the pressurized air supply unit, and extracting unadsorbed oxygen from the end of the concentrated oxygen gas outlet side of the adsorption cylinder (pressurized adsorption process).

[0054] The process of equalizing the pressure in multiple adsorption cylinders (pressure equalization process);

[0055] The process of depressurizing the adsorption cylinder, desorbing the adsorbed nitrogen, and discharging it into the outside air (depressurization and desorption process);

[0056] The process of pre-pressurizing the already depressurized adsorption cylinder (pre-pressurization process); and

[0057] The process of equalizing the pressure in multiple adsorption cylinders (pressure equalization process); and

[0058] When a pressure adsorption process is performed in one or a group of adsorption cells, a depressurization desorption process and a pre-pressurization process are performed in another or a different group of adsorption cells.

[0059] [Advantages of the Invention]

[0060] According to this embodiment, preventing a drop in pilot pressure (the discharge pressure of the pressurized air supply unit, the internal pressure of the concentrated oxygen gas tank, or the internal pressure of the adsorption cylinder) during the pressure equalization step helps to easily maintain the pilot pressure equal to or higher than the minimum operating pressure of the pilot-operated solenoid valve, even under low flow rate operation, thereby enabling control of the rotational speed of the pressurized air supply unit and thus suppressing power consumption.

[0061] In addition, reducing the rotation speed of the pressurized air supply unit can reduce the air supply volume, which has the effect of suppressing excessive oxygen adsorption. When the extraction flow rate is low relative to the air supply volume, excessive oxygen adsorption will occur.

[0062] The objects and advantages of this invention can be identified and obtained by means of the elements and combinations particularly pointed out in the claims. The above general description and the following detailed description are exemplary and explanatory, and are not intended to limit the claimed invention. Attached Figure Description

[0063] Figure 1 This is a functional block diagram of an oxygen concentrator according to an embodiment.

[0064] Figure 2 This is a diagram illustrating the opening / closing operations of the controlled supply flow path opening / closing unit, exhaust flow path opening / closing unit, and connecting flow path opening / closing unit in an oxygen concentrator according to an embodiment. Figure 2 (a) illustrates the opening / closing operation of the general prior art, and Figure 2 (b) shows an example of the opening / closing operation of an oxygen concentrator in an embodiment of the present invention.

[0065] Figure 3 This is a diagram illustrating the airflow in an oxygen concentrator according to an embodiment, by controlling the airflow of the supply flow path opening / closing unit, the exhaust flow path opening / closing unit, and the opening / closing unit connecting the flow path opening / closing unit. Figure 3 (a) illustrates the airflow of the general prior art, and Figure 3 (b) shows an example of airflow through the opening / closing operation of an oxygen concentrator according to an embodiment of the present invention.

[0066] Figure 4 This is a diagram illustrating the changes in the discharge pressure (Comp discharge pressure) of the pressurized air supply unit, the internal pressure of each adsorption cartridge, and the internal pressure of the concentrated oxygen gas tank by controlling the opening / closing units of the supply flow path opening / closing unit, the exhaust flow path opening / closing unit, and the connecting flow path opening / closing unit in the oxygen concentrator according to the embodiment. Figure 4 (a) illustrates pressure changes in the general prior art, and Figure 4 (b) shows an example of pressure variation in an oxygen concentrator according to an embodiment of the present invention. Detailed Implementation

[0067] An oxygen concentrator, control method, and control procedure according to one aspect of the present invention will be described below with reference to the accompanying drawings. However, it should be noted that the scope of this disclosure is not limited to those embodiments, but extends to the invention described in the claims and its equivalents. In the following description and drawings, components having the same functional configuration are indicated by the same reference numerals, thereby omitting redundant descriptions.

[0068] [Summary of an oxygen concentrator according to an embodiment]

[0069] Figure 1 This is a functional block diagram of an oxygen concentrator according to an embodiment.

[0070] The oxygen concentrator includes: multiple adsorption cartridges (4A and 4B) filled with an adsorbent that preferentially adsorbs nitrogen rather than oxygen; a pressurized air supply unit (1) that supplies pressurized air to the adsorption cartridges; a pair of supply flow path opening / closing units (2A, 2B) that connect the pressurized air supply unit and the adsorption cartridges and open / close the gas flow path of the pressurized air; a pair of exhaust flow path opening / closing units (3A, 3B) that open / close the gas flow path for atmospheric release and exhausting the adsorption cartridges; a concentrated oxygen gas tank (7) that stores concentrated oxygen gas generated by the multiple adsorption cartridges; a connecting flow path opening / closing unit (pressure equalization / flushing) (5) that connects to the end of each adsorption cartridge on the concentrated oxygen gas outlet side and allows a portion of the generated concentrated oxygen gas to pass through it; and a flow path opening / closing control unit that controls the opening / closing of the supply flow path opening / closing unit (2A, 2B), the exhaust flow path opening / closing unit (3A, 3B), and the connecting flow path opening / closing unit (pressure equalization / flushing) (5). Although a connected flow path opening / closing unit with one flow path is shown here, a configuration with independent flow paths for pressure equalization and flushing can be used.

[0071] The opening and closing of the flow path is controlled by a flow path opening / closing control unit for supplying the flow path opening / closing units (2A, 2B), exhausting the flow path opening / closing units (3A, 3B), and connecting the flow path opening / closing unit (pressure equalization / flushing) (5). The supply flow path opening / closing units (2A, 2B), exhausting the flow path opening / closing units (3A, 3B), and connecting the flow path opening / closing unit (pressure equalization / flushing) (5) are, for example, solenoid valves and control valves (solenoid valves, piezoelectric valves), and are controlled according to signals input from the flow path opening / closing control unit. The flow path opening / closing control unit has one or more processors and their peripheral circuitry. The flow path opening / closing control unit integrates the control of the oxygen concentrator's operation and is a processor, such as, for example, a microcontroller unit (MCU).

[0072] An oxygen concentrator performs an oxygen generation process that produces concentrated oxygen gas from raw air and delivers the concentrated oxygen gas to the nostrils of the user or patient using the oxygen concentrator.

[0073] Although Figure 1 This indicates the components related to the function of generating concentrated oxygen gas, but the oxygen concentrator may be equipped with an external air intake filter, check valve, pressure regulating valve, flow rate setting unit, humidifier, filter, etc.

[0074] First, raw material air is drawn in from the outside through an air inlet equipped with an external air filter or similar device to remove foreign matter such as dust. A pressurized air supply unit (1) compresses the air drawn in through the external air filter to generate pressurized air, which is then supplied to either of a pair of adsorption cylinders (4A and 4B) via a supply flow path opening / closing unit (2A, 2B). The pressurized air supply unit (1) is also called a compressor, and examples include oscillating air compressors and rotary air compressors, such as screw, rotary, and scroll compressors.

[0075] A pair of adsorption cylinders (4A and 4B) are filled with zeolite adsorbent, which selectively adsorbs nitrogen gas rather than oxygen gas in pressurized air. The zeolite selectively adsorbs approximately 77% of the nitrogen gas contained in the pressurized air supplied from the pressurized air supply unit (1).

[0076] A pair of adsorption cartridges (4A and 4B) adsorb nitrogen gas and generate oxygen gas from pressurized air supplied by a pressurized air supply unit (1) via a supply flow path opening / closing unit (2A, 2B). While adsorption cartridge (4A) generates oxygen gas, adsorption cartridge (4B) discharges the adsorbed nitrogen gas to the outside of the oxygen concentrator via an exhaust flow path opening / closing unit (3B). When the nitrogen gas adsorbed by adsorption cartridge (4A) is discharged to the outside of the oxygen concentrator via an exhaust flow path opening / closing unit (3A), adsorption cartridge (4B) generates oxygen gas. Oxygen gas is generated alternately between the pair of adsorption cartridges (4A and 4B), thereby enabling the oxygen concentrator to continuously generate oxygen gas. Although an oxygen concentrator has been described using a pair of adsorption cartridges (4A and 4B) as an example, the oxygen concentrator according to the embodiment may have three or more adsorption cartridges. When three or more adsorption cartridges are provided, the operation is performed in such a way that the adsorption and desorption steps can be repeated sequentially between the multiple adsorption cartridges. For example, in the case of a three-tube type with three adsorption tubes (4A, 4B, and 4C), control is performed by switching the tubes in the following sequence: when adsorption tube (4A) is in the adsorption step, a set of adsorption tubes (4B and 4C) is in the desorption step; when adsorption tube (4B) is in the adsorption step, a set of adsorption tubes (4C and 4A) is in the desorption step; when adsorption tube (4C) is in the adsorption step, a set of adsorption tubes (4A and 4B) is in the desorption step.

[0077] The supply flow path opening / closing unit and / or exhaust flow path opening / closing unit are pilot-operated solenoid valves. The pilot-operated solenoid valves utilize pilot pressure (air pressure) to switch the operation of the main valve. The source of the pilot pressure can be the discharge pressure of the pressurized air supply unit, the internal pressure of the concentrated oxygen gas tank, or the internal pressure of the adsorption cylinder, with the discharge pressure of the pressurized air supply unit, in particular, being utilized to the greatest extent. The pilot pressure varies depending on the characteristics of the pilot-operated solenoid valve used, but this specification shows examples requiring 40 kPa or higher. The pilot pressure is allowed to temporarily drop below the minimum operating pressure of the pilot-operated solenoid valve, provided the pressure does not impede the opening and closing of the pilot-operated solenoid valve. Although the oxygen concentrator is more efficient if both the supply flow path opening / closing unit and the exhaust flow path opening / closing unit are pilot-operated solenoid valves, the present invention also addresses the case where either one is a pilot-operated solenoid valve.

[0078] A pair of check valves (6A and 6B) are provided between each of the pair of adsorption cylinders (4A and 4B) and the concentrated oxygen gas tank (7). The check valves (6A, 6B) between the adsorption cylinders (4A and 4B) and the concentrated oxygen gas tank (7) prevent the concentrated oxygen gas from flowing back to the adsorption cylinder side when the internal pressure of the concentrated oxygen gas tank becomes higher than the internal pressure of the adsorption cylinder. When the adsorption cylinder (4A) generates oxygen gas, the check valve (6A) is open, allowing the concentrated oxygen gas generated by the adsorption cylinder (4A) to flow into the concentrated oxygen gas tank (7). Furthermore, when the nitrogen gas adsorbed by the adsorption cylinder (4B) is discharged to the outside of the oxygen concentrator through the exhaust flow path opening / closing unit (3B), the check valve (6B) is closed, preventing the concentrated oxygen gas stored in the concentrated oxygen gas tank (7) from being discharged to the outside of the oxygen concentrator through the adsorption cylinder (4B).

[0079] An oxygen concentrate tank (7) (also called a product tank) stores oxygen gas generated by each of a pair of adsorption cylinders (4A and 4B). The internal pressure of the oxygen concentrate tank (7) fluctuates depending on the internal pressure variations associated with the generation of concentrated oxygen gas in each of the adsorption cylinders (4A and 4B). In order to maintain the pressure of the concentrated oxygen gas delivered from the oxygen concentrate tank (7) with internal pressure fluctuations associated with the generation of concentrated oxygen gas at a predetermined level, a pressure regulating valve, such as a pressure reducing valve, is provided.

[0080] By adjusting the opening of the solenoid valve of the flow rate control unit according to the flow rate output signal input from the control unit, the concentrated oxygen gas extracted from the concentrated oxygen gas tank (7) is controlled to flow at a predetermined flow rate.

[0081] Concentrated oxygen gas, adjusted to a predetermined flow rate (from which foreign matter (such as dust generated during the production of concentrated oxygen gas) is removed by an air filter), is moderately humidified by a humidifier to prevent dryness from the user's nostrils to the respiratory tract, and supplied to the user from the end of a flow path (such as an intubation tube).

[0082] The concentration and flow rate of concentrated oxygen gas can be measured by connecting a concentration sensor and a flow rate sensor in the concentrated oxygen gas flow path between the air filter of the outlet filter and the humidifier.

[0083] [control]

[0084] In the oxygen concentrator according to the embodiment, the pressure in the adsorption cartridge is controlled to prevent a drop in the pilot pressure supplied to the pilot-operated solenoid valve used in at least one of the supply flow path opening / closing unit or the exhaust flow path opening / closing unit. For this purpose, a flow path opening / closing control unit is provided, which performs opening / closing control of the supply flow path opening / closing unit (2A, 2B), the exhaust flow path opening / closing unit (3A, 3B), and the connecting flow path opening / closing unit (5). Refer to Figures 2 to 4 Explain the pressure control within the adsorption cylinder.

[0085] As described above, by alternating adsorption and desorption steps between multiple adsorption cartridges, the oxygen concentrator can continuously produce concentrated oxygen gas. First, along... Figure 2 and Figure 3 The document will describe the opening / closing operations of the controlled supply flow path opening / closing unit, exhaust flow path opening / closing unit, and connecting flow path opening / closing unit in the oxygen concentrator according to the embodiment, as well as the airflow generated by the controlled opening / closing operations of the supply flow path opening / closing unit, exhaust flow path opening / closing unit, and connecting flow path opening / closing unit in the oxygen concentrator according to the embodiment.

[0086] Figure 2 (a) illustrates the opening / closing operation of the general prior art, and Figure 2 (b) shows an example of the opening / closing operation of the oxygen concentrator in an embodiment of the present invention.

[0087] exist Figure 2 (b) In examples T1 and T4, both adsorption cylinders (4A and 4B) are in the pressure equalization step, both supply flow path open / close units (2A and 2B) are in the open state, both exhaust flow path open / close units (3A and 3B) are in the closed state, and the connecting flow path open / close unit (5) is in the open state. The adsorption cylinders (4A and 4B) are connected to each other via the supply flow path open / close units (2A and 2B) and the connecting flow path open / close unit (5) (see Figure 3(b) and thus pressure equalization. Even when the connecting flow path opening / closing unit (5) is closed, pressure equalization (2A, 2B) can be achieved by opening only the two supply flow path opening / closing units. Here, pressure equalization can be achieved even when the connecting flow path opening / closing unit (5) is open and only one supply flow path opening / closing unit is open, but having both supply flow path opening / closing units (2A, 2B) open allows for rapid pressure equalization. Note that T1 and T4 correspond to the "pressure equalization step of equalizing the pressure in multiple adsorption cylinders" and "pressure equalization step of equalizing the pressure in multiple adsorption cylinders" in claims, respectively. The times of T1 and T4 are preferably determined by the time until the pressures of adsorption cylinders (4A) and (4B) become the same, or can be shorter.

[0088] In this specification, low flow rate operation is defined as being performed using oxygen gas in a flow rate range of 0.1 LPM or higher and less than 2.00 LPM.

[0089] like Figure 2 As shown in (b), T2 / T5 is a depressurized desorption step for one adsorption cylinder (T2_4A / T5_4B) and a pressurized adsorption step for the other adsorption cylinder (T2_4B / T5_4A). In this case, for the adsorption cylinder (T2_4A / T5_4B) in the depressurized desorption step, the supply flow path opening / closing unit (T2_2A / T5_2B) is closed, the exhaust flow path opening / closing unit (T2_3A / T5_3B) is open, and the connecting flow path opening / closing unit (5) is closed. On the other hand, for the adsorption cylinder (T2_4B / T5_4A) in the pressurized adsorption step, the supply flow path opening / closing unit (T2_2B / T5_2A) is open, and the exhaust flow path opening / closing unit (T2_3B / T5_3A) is closed. During the depressurization desorption step, the pressure in the adsorption cylinders (T2_4A / T5_4B) decreases because the supply flow path opening / closing unit (T2_2A / T5_2B) closes and the exhaust flow path opening / closing unit (T2_3A / T5_3B) opens to the air, thereby desorbing the nitrogen gas adsorbed on the adsorbent and discharging it into the outside air (see [link]). Figure 3(b)). The adsorption cylinders (T2_4B / T5_4A) in the pressurized adsorption step are pressurized by supplied pressurized air, and concentrated oxygen gas is generated by adsorbing nitrogen gas in the air onto the adsorbent in the adsorption cylinders (T2_4B / T5_4A). The generated concentrated oxygen gas is then transported to the concentrated oxygen gas tank (7) via a check valve (T2_6B / T5_6A) (see Figure 3 (b) Although there is no particular limitation on the T2 / T5 time, as long as the desired oxygen concentration can be obtained, it is preferable to extend the time to further desorb the adsorbed nitrogen until the internal pressure of the adsorption tube becomes as low as possible.

[0090] like Figure 2 As shown in (b), T3-1 / T6-1 is a flushing step for one adsorption cylinder (T3-1_4A / T6-1_4B), during which a portion of the concentrated oxygen gas generated in the adsorption cylinder during pressurized adsorption is supplied to the adsorption cylinder during depressurized desorption. The other adsorption cylinder (T3-1_4B / T6-1_4A) continues the pressurized adsorption step of the previous step. In this case, for the adsorption cylinder (T3-1_4A / T6-1_4B) in the flushing step, the supply flow path opening / closing unit (T3-1_2A / T6-1_2B) is in the closed state, the exhaust flow path opening / closing unit (T3-1_3A / T6-1_3B) is in the open state, and the connecting flow path opening / closing unit (5) is in the open state. On the other hand, regarding the adsorption cylinders (T3-1_4B / T6-1_4A) in the pressurized adsorption step, the supply flow path opening / closing unit (T3-1_2B / T6-1_2A) is continuously in the open state, and the exhaust flow path opening / closing unit (T3-1_3B / T6-1_3A) is in the closed state. In the adsorption cylinders (T3-1_4A / T6-1_4B) in the rinsing step, the connecting flow path opening / closing unit (5) is changed to the open state, which connects the adsorption cylinders (4A) and (4B) to each other at the end of the concentrated oxygen gas outlet side, and a portion of the concentrated oxygen gas is returned as rinsing gas from the adsorption cylinder (T3-1_4B / T6-1_4A) in which concentrated oxygen gas is generated in the pressurized adsorption step to the other adsorption cylinder (T3-1_4A / T6-1), thereby expelling the desorbed nitrogen gas, resulting in an increase in the desorption efficiency of nitrogen gas from the adsorbent in the depressurized desorption step (see Figure 3(b)). In the adsorption cylinder (T3-1_4B / T6-1_4A) during the pressurized adsorption step, although the airflow remains unchanged compared to the previous step, the continuous supply of pressurized air increases the adsorption of nitrogen on the adsorbent in the adsorption cylinder (T3-1_4B / T6-1_4A) to produce concentrated oxygen gas, and the produced concentrated oxygen gas is delivered to the concentrated oxygen gas tank (7) via the check valve (T3-1_6B / T6-1_6A) (see Figure 3 (b) Although the time for T3-1 / T6-1 can be any length, as long as the desired oxygen concentration can be obtained, it is preferable to set the time in such a way that oxygen continues to be generated in the pressurized adsorption tube, more of the adsorbed nitrogen is desorbed in the depressurized adsorption tube, and the desorbed nitrogen is completely discharged.

[0091] Note that, although Figure 2 An example is shown, and as a more preferred example, rinsing is performed in the latter half of the depressurization desorption step. However, if the desired oxygen concentration can be obtained without rinsing, the rinsing step (T3-1 / T6-1) can be omitted. Furthermore, since the rinsing step (T3-1 / T6-1) is the step in which a portion of the concentrated oxygen gas generated in the adsorption chamber during pressurized adsorption is supplied to the adsorption chamber during depressurized desorption, the time for the depressurization desorption step (T2 / T5) which only performs depressurization desorption can be omitted, and if the desired oxygen concentration can be obtained, it is controlled to be performed as a rinsing step (T3-1 / T6-1), in which depressurization desorption and rinsing are performed simultaneously. In this case, the time is also preferably set in such a way that oxygen continues to be generated in the pressurized side adsorption chamber, and the desorbed nitrogen is completely discharged from the depressurized side adsorption chamber. Note that although... Figure 2 Treating the "rinsing step" and the "desorption / reduction step" as different steps makes the rinsing step (T3-1 / T6-1) perform after the desorption / reduction step (T2 / T5). However, since rinsing means flushing a portion of the concentrated oxygen gas generated in the adsorption tube during pressurized adsorption into the adsorption tube during desorption / reduction, it is possible that the rinsing step is included as an aspect of the desorption / reduction step, and therefore it is sometimes expressed as "rinsing is performed in the latter half of the desorption / reduction step".

[0092] like Figure 2As shown in (b), T3-2 / T6-2 is a pre-pressurization step for one adsorption cylinder (T3-2_4A / T6-2_4B), and the other adsorption cylinder (T3-2_4B / T6-2_4A) continues the previous pressurization adsorption step. In the pre-pressurization step of the adsorption cylinder (T3-2_4A / T6-2_4B), the exhaust flow path opening / closing unit (T3-2_3A / T6-2_3B) switches from the open state in the previous step (from the depressurization desorption step to the rinsing step) to the closed state. When the exhaust flow path opening / closing unit (T3-2_3A / T6-2_3B) changes to the closed state, the already depressurized adsorption cylinder (T3-2_4A / T6-2_4B) will begin pressurization before the next pressure equalization step, and the cylinder pressure of the depressurized adsorption cylinder (T3-2_4A / T6-2_4B) can be pre-increased (…). Figure 4 (b)). In the adsorption cylinder (T3-1_4B / T6-1_4A) during the pressurized adsorption step, although the airflow remains unchanged compared to the previous step, the continuous supply of pressurized air maintains the pressure in the adsorption cylinder (T3-2_4B / T6-2_4A) and increases nitrogen adsorption on the adsorbent to produce concentrated oxygen gas. The produced concentrated oxygen gas is then transported to the concentrated oxygen gas tank (7) via a check valve (T3-2_6B / T6-2_6A) (see Figure 3 (b) The time for T3-2 / T6-2 can be adjusted depending on the required pre-pressurization conditions, and the time is not important as long as the required oxygen concentration is obtained.

[0093] Throughout steps T1 to T6-2, an adsorption and desorption cycle is completed in an adsorption chamber, and by repeating this cycle, concentrated oxygen gas can be continuously produced. The cycle time is not important as long as the produced oxygen concentration reaches the specified value. Figure 4As shown in (b), as a result of the pre-pressurization step of pre-pressurizing the already depressurized internal components in the adsorption cylinders (T1_4B / T4_4A), the depressurized side adsorption cylinders can begin pressure equalization from a state of increased cylinder pressure, thereby preventing pressure drop in both cylinders during the pressure equalization step. As a result, the depressurized adsorption cylinders (T1_4B / T4_4A) and the pressurized adsorption cylinders (T1_4A / T4_4B) are pressure equalized, and the equalized pressure becomes higher than that obtained by conventional methods, thereby preventing a drop in the discharge pressure of the pressurized air supply unit and a drop in the internal pressure of the concentrated oxygen gas tank. As a result, in low-flow-rate operation, the compressor speed is reduced whenever conditions allow, and power consumption can be suppressed without worrying about the minimum operating pressure limitation of the pilot-operated solenoid valve. Furthermore, the reduction in compressor speed allows for the suppression of excessive oxygen adsorption that occurs when the extraction flow rate is low relative to the air supply. On the other hand, since the internal pressure fluctuation of the concentrated oxygen gas tank is reduced, fluctuations in the product flow rate are also suppressed.

[0094] This technology can be applied to any oxygen concentrator, as long as it is a continuous flow type, whether stationary or portable.

[0095] [List of reference numerals]

[0096] 1. Pressurized air supply unit

[0097] 2B 2A Supply flow path opening / closing unit

[0098] 3B 3A Exhaust flow path opening / closing unit

[0099] 4B 4A Adsorption cylinder

[0100] 5 Connecting Flow Path Open / Close Unit

[0101] 6A, 6B check valves

[0102] 7. Concentrated Oxygen Gas Tank

Claims

1. An oxygen concentrator, comprising: Multiple adsorption cartridges filled with an adsorbent that preferentially adsorbs nitrogen gas rather than oxygen gas; A pressurized air supply unit is used to supply pressurized air to the adsorption cylinder; A supply flow path opening / closing unit is used to connect the pressurized air supply unit and each adsorption cylinder, and to open / close the gas flow path of the pressurized air; An exhaust flow path opening / closing unit is used to open / close the gas flow path for discharging gas from each adsorption cell; A concentrated oxygen gas tank for storing concentrated oxygen gas produced by the plurality of adsorption cylinders; and The flow path opening / closing unit connects to the end of each adsorption cartridge on the concentrated oxygen gas outlet side, allowing a portion of the generated concentrated oxygen gas to pass through it. A pilot-operated solenoid valve used in at least one of the supply flow path opening / closing unit or the exhaust flow path opening / closing unit. The oxygen concentrator includes a flow path opening / closing control unit for controlling the opening / closing of the supply flow path opening / closing unit, the exhaust flow path opening / closing unit, and the connecting flow path opening / closing unit. The flow path opening / closing control unit performs control in each adsorption cartridge in such a way that the following steps are repeated in the listed order. (a) The pressure adsorption step involves supplying pressurized air to adsorb nitrogen from the pressurized air onto the adsorbent in the adsorption cylinder, and extracting unadsorbed oxygen from the end of the concentrated oxygen gas outlet side of the adsorption cylinder. (b) Pressure equalization step, equalizing the pressure in the plurality of adsorption cylinders; (c) Depressurization and desorption step: depressurize the adsorption cylinder, desorb the adsorbed nitrogen, and discharge it into the outside air; (d) Pre-pressurization step: Pre-pressurizing the already depressurized adsorption cylinder; and (e) Pressure equalization step, equalizing the pressure in the multiple adsorption cylinders. This allows for the execution of (a) pressure adsorption steps in one or more adsorption cartridges, and (c) depressurization desorption steps and (d) pre-pressurization steps in another or a different set of adsorption cartridges. During the (d) pre-pressurization step, the flow path opening / closing control unit controls the exhaust flow path opening / closing unit from the adsorption cylinder during pre-pressurization to be closed, controls the supply flow path opening / closing unit to the adsorption cylinder during pre-pressurization to be closed, and controls the connecting flow path opening / closing unit to be open.

2. The oxygen concentrator according to claim 1, wherein, During the pressure equalization steps (b) and (e), the flow path opening / closing control unit controls all the supply flow path opening / closing units of the plurality of adsorption cylinders to be in the open state.

3. The oxygen concentrator according to claim 1 or 2, wherein, The flow path opening / closing control unit controls, in the latter half of step (c) depressurization desorption, to flush a portion of the concentrated oxygen gas generated in the adsorption cartridge during pressurized adsorption into the adsorption cartridge during depressurization desorption.

4. The oxygen concentrator according to claim 1 or 2, wherein, During the decompression and desorption step (c), the flow path opening / closing control unit controls the connected flow path opening / closing unit to be in a closed state.

5. The oxygen concentrator according to claim 4, wherein, During the pressure equalization steps (b) and (e), the flow path opening / closing control unit controls the connected flow path opening / closing unit to be in the open state.

6. A control method for an oxygen concentrator, used to control the pressure in a plurality of adsorption cartridges to prevent a drop in the pilot pressure supplied to a pilot-operated solenoid valve, said pilot-operated solenoid valve being used in at least one of a supply flow path opening / closing unit or an exhaust flow path opening / closing unit. in, In each adsorption cartridge, control is performed in such a manner that the following steps are repeated in the listed order. The pressurized adsorption step involves supplying pressurized air from the pressurized air supply unit to the adsorption cylinder, adsorbing nitrogen from the pressurized air onto the adsorbent in the adsorption cylinder, and extracting unadsorbed oxygen from the end of the concentrated oxygen gas outlet side of the adsorption cylinder. The pressure equalization step equalizes the pressure in the multiple adsorption cylinders; The decompression desorption step involves depressurizing the adsorption cylinder, desorbing the adsorbed nitrogen, and releasing it into the outside air. The pre-pressurization step involves pre-pressurizing the already depressurized adsorption cylinder. and The pressure equalization step equalizes the pressure in the multiple adsorption cylinders. This allows for the simultaneous execution of a pressure adsorption step in one or more adsorption cartridges, and a depressurization and pre-pressurization step in another or a different set of adsorption cartridges. During the pre-pressurization step, the exhaust flow path opening / closing unit from the adsorption cylinder during pre-pressurization is controlled to be closed, the supply flow path opening / closing unit to the adsorption cylinder during pre-pressurization is controlled to be closed, and the connecting flow path opening / closing unit is controlled to be open.

7. A storage medium storing a control program for an oxygen concentrator for controlling the pressure in a plurality of adsorption cartridges to prevent a drop in the pilot pressure supplied to a pilot-operated solenoid valve, the pilot-operated solenoid valve being used in at least one of a supply flow path opening / closing unit or an exhaust flow path opening / closing unit. The control program executes the following process in each adsorption cell, repeating the process in the listed order. The process of supplying pressurized air from a pressurized air supply unit to an adsorption cylinder, adsorbing nitrogen from the pressurized air onto the adsorbent in the adsorption cylinder, and extracting unadsorbed oxygen from the end of the concentrated oxygen gas outlet side of the adsorption cylinder (pressurized adsorption process). The process of equalizing the pressure in the multiple adsorption cylinders is called the pressure equalization process. The process of depressurizing the adsorption cylinder, desorbing the adsorbed nitrogen, and discharging it into the outside air is called depressurization desorption process. The process of pre-pressurizing the already depressurized adsorption cylinder is called the pre-pressurization process. and The process of equalizing the pressure in the multiple adsorption cylinders is called the pressure equalization process. In the aforementioned process, while a pressure adsorption process is performed in one or a group of adsorption cylinders, a depressurization desorption process and a pre-pressurization process are performed in another or a different group of adsorption cylinders. During the pre-pressurization step, the process includes controlling the exhaust flow path opening / closing unit from the adsorption cylinder during pre-pressurization to a closed state, controlling the supply flow path opening / closing unit to the adsorption cylinder during pre-pressurization to a closed state, and controlling the connecting flow path opening / closing unit to an open state.

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