JP4404583B2 - Oxygen concentrator - Google Patents

Description

  The present invention relates to a pressure fluctuation adsorption type oxygen concentrator.

  Conventionally, an adsorption chamber that contains an adsorbent that selectively adsorbs nitrogen in the air, a compressor that sends air to the adsorption chamber, and a storage tank that temporarily stores product gas delivered from the adsorption chamber There is known a pressure fluctuation adsorption type oxygen concentrator equipped with This oxygen concentrator repeatedly performs a nitrogen adsorption operation for adsorbing nitrogen in the air to the adsorbent accommodated in the adsorption chamber, and a nitrogen desorption operation for desorbing the nitrogen adsorbed by the adsorbent and discharging it to the atmosphere. Air in which the oxygen concentration is increased by the nitrogen adsorption process (hereinafter sometimes referred to as oxygen-enriched gas) is continuously supplied to the storage tank as product gas. The nitrogen adsorption operation is performed by pressurizing the adsorption chamber with a compressor. The nitrogen desorption operation is performed by opening the adsorption chamber to the atmosphere and reducing the pressure, thereby regenerating the nitrogen adsorption ability of the adsorbent. The product gas supplied to the storage tank is temporarily stored in the storage tank and then taken out.

  In recent years, in response to the increase in the number of patients suffering from respiratory diseases such as asthma and bronchitis, such oxygen concentrators have come to be used in homes for home medical use. . The patient inhales product gas by connecting a nasal cannula or nasal mask to an oxygen concentrator. The flow rate of the product gas that the patient inhales is determined by the doctor's prescription. For this reason, the general oxygen concentrator allows the patient to set the product gas extraction flow rate. However, on the other hand, most of the motors that drive the compressor are always driven at a constant voltage. For this reason, in such an oxygen concentrator, the power consumption is always constant and the power may be excessively consumed despite the setting change of the product gas extraction flow rate. Many medical oxygen concentrators are operated day and night, and such excessive consumption of electric power increases the economic burden. So far, oxygen concentrators developed for power saving have been proposed that can control the drive voltage of the compressor.

  For example, Japanese Patent Laid-Open No. 2000-354630 (Patent Document 1) discloses an adsorption tower containing an adsorbent that separates and adsorbs oxygen and nitrogen from the air, an electric compressor that sends compressed air to the adsorption tower, and oxygen concentration. Oxygen comprising a storage tank for storing gas, a conduit for taking out the oxygen-enriched gas and supplying it to the user, and a control means for controlling the adsorption process and desorption work of the adsorption tower to be alternately repeated by an automatic opening / closing valve In the concentrator, there is described an oxygen concentrator characterized by comprising a control means for controlling the drive voltage of the electric compressor in relation to the flow rate setting means for setting the flow rate of the oxygen enriched gas. At this time, it is also described that the drive voltage of the compressor is controlled by a change in the internal pressure of the storage tank. Thereby, it is said that it becomes possible to reduce power consumption while operating the oxygen concentrator stably.

  Japanese Patent Application Laid-Open No. 11-207128 (Patent Document 2) discloses an adsorption chamber containing an adsorbent capable of selectively adsorbing oxygen from the air, a blowing means for supplying air to the adsorption chamber, and an adsorption chamber. A product for determining the flow rate of gas taken out through the gas extraction means in an oxygen concentrator comprising a gas storage means for storing the extracted oxygen-enriched gas and a gas extraction means for extracting the oxygen-enriched gas from the gas storage means A gas extraction flow rate setting means, a supply air flow rate setting means for determining the flow rate of air supplied to the adsorption chamber via the blower means in accordance with the product gas extraction flow rate, and a product gas extraction flow rate in the adsorption chamber. An oxygen concentrator comprising a pressurization time determining means for determining the gas pressurization time is described. As a result, it is said that it is possible to reduce the power consumption and to extract the product gas with a high oxygen yield. At this time, it is also described that the capacity of the compressor is controlled in accordance with the determined supply air flow rate.

JP 2000-354630 A (claims, page 2, FIG. 1) JP-A-11-207128 (Claims, page 3, drawing)

  However, although Patent Document 1 describes performing so-called threshold control such as reducing the compressor drive voltage when the internal pressure of the storage tank reaches a predetermined value, the compressor drive voltage is However, there is no description about changing in relation to the actual product gas extraction flow rate. Patent Document 2 describes changing the capacity of a compressor in accordance with a product gas extraction flow rate setting value set by a patient. However, in this case, the reference for change is a set value to the last, and there is no description about changing according to the actual product gas extraction flow rate. For this reason, in any oxygen concentrator, if there is an abnormality in the actual product gas extraction flow rate, control may not be performed properly. For example, if the actual product gas extraction flow rate is lower than the desired product gas extraction flow rate due to some cause such as tube breakage, the occurrence of the abnormality may not be detected. In order to detect this, if a flow meter such as a mass flow meter is newly installed, not only the size and weight of the oxygen concentrator increases, but also its manufacturing cost increases.

  The present invention has been made in order to solve the above-described problems, and various operating conditions such as the air delivery flow rate of the compressor can be changed in relation to the flow rate of the product gas actually taken out from the storage tank. An object is to provide a possible oxygen concentrator. It is also an object of the present invention to provide an oxygen concentrator that is appropriately controlled even when the flow rate of the product gas actually taken out from the storage tank is abnormal.

  The above problem is that a plurality of adsorption chambers that contain an adsorbent that selectively adsorbs nitrogen in the air, a compressor that sends air to the adsorption chamber, and a product gas delivered from the adsorption chamber are temporarily stored. In the pressure fluctuation adsorption oxygen concentrator equipped with a storage tank, a storage tank pressure detecting means for detecting the internal pressure of the storage tank is provided, and the pressure reduction calculated from the detected internal pressure data of the storage tank This is solved by providing an oxygen concentrator characterized in that the operating conditions are automatically changed according to the speed α. Here, the pressure decrease rate α refers to a decrease amount per predetermined time of the internal pressure of the storage tank. The pressure decrease rate α is proportional to the flow rate of the product gas actually taken out from the storage tank. As a result, various operating conditions of the oxygen concentrator can be changed in relation to the flow rate of the product gas actually taken out from the storage tank.

  In a preferred embodiment, the air delivery flow rate of the compressor is changed more as the pressure reduction rate α is higher, and is changed less as the pressure reduction rate α is lower. As a result, the power consumed by the compressor can be reduced. At this time, it is more preferable that the rotation speed of the cooling fan that cools the compressor is changed faster as the pressure reduction rate α is increased, and is changed more slowly as the pressure reduction rate α is decreased. Thereby, it is also possible to reduce power consumed by the cooling fan and noise generated from the cooling fan.

Adsorption chamber pressure detection means for detecting the internal pressure of the adsorption chamber is provided, and when the internal pressure of the adsorption chamber detected by the adsorption chamber pressure detection means reaches the upper limit P ₀ , the pressure equalization operation of the adsorption chamber is started. This is also a preferred embodiment. This makes it possible to concentrate oxygen at an efficient pressure suitable for the actual product gas extraction flow rate. At this time, it is more preferable that the upper limit value P ₀ is changed to be higher as the pressure reduction rate α becomes higher and changed to be lower as the pressure reduction rate α becomes slower.

  It is also a preferred embodiment that the time during which the pressure equalizing operation of the adsorption chamber is performed is changed longer as the pressure reduction rate α becomes faster and shorter as the pressure reduction rate α becomes slower. As a result, it is possible to concentrate oxygen by adopting an efficient equalization time suitable for the actual product gas extraction flow rate.

  It is also a preferred embodiment that the operating condition is selected from a combination of a plurality of preset operating conditions. If the operating conditions are continuously changed in a stepless manner, the control may become too complicated, but the control should be simplified by changing the operating conditions in multiple steps. Is possible.

  A variable valve capable of continuously adjusting the gas flow rate is provided in a gas flow path for taking out product gas from the storage tank, and the opening degree of the variable valve is also finely adjusted according to the pressure reduction rate α. It is. Examples of the variable valve that can continuously adjust the gas flow rate include a mass flow controller. Most conventional oxygen concentrators can adjust the actual product gas extraction flow rate to only a few stages, but this allows the actual product gas extraction flow rate to be adjusted continuously (steplessly). Can be optimized.

  It is preferable that the operating conditions are not changed until a predetermined time elapses after the oxygen concentrator is activated. The internal pressure of the storage tank is often unstable immediately after the oxygen concentrator is started. For this reason, it is difficult to obtain an accurate product gas extraction flow rate from the pressure reduction rate α, which may cause problems in the operation of the oxygen concentrator. During this period, it is more preferable to follow the operating conditions that can concentrate oxygen most efficiently (the operating conditions selected when the product gas extraction flow rate is maximized). Thereby, the internal pressure of the storage tank can be stabilized in a short time. It is also possible to reliably rotate the compressor motor at startup. When a predetermined time elapses after the oxygen concentrator is activated, normal operation (operation in which operating conditions are changed) is started.

In addition, the above problem is that a plurality of adsorption chambers that contain an adsorbent that selectively adsorbs nitrogen in the air, a compressor that discharges air to the adsorption chamber, and a product gas that is delivered from the adsorption chamber temporarily In a pressure fluctuation adsorption type oxygen concentrator equipped with a storage tank to be stored, a storage tank pressure detection means for detecting the internal pressure of the storage tank, and an alarm means for issuing an alarm when an abnormality occurrence signal is input A pressure reduction rate α calculated from the detected internal pressure of the storage tank is monitored, and when an abnormality in the pressure reduction rate α is detected, an abnormality occurrence signal is input to the alarm means It is also solved by providing a concentrator. Thereby, when there is an abnormality in the flow rate of the product gas actually taken out from the storage tank, it is possible to detect the occurrence of the abnormality. For example, when the actual product gas extraction flow rate is lower than the desired product gas extraction flow rate due to some cause such as tube breakage, the occurrence of the abnormality can be detected. However, during the period from when the oxygen concentrator is activated until a predetermined time has passed, an abnormality signal should not be input to the alarm means, except when an emergency such as a power failure or overcurrent occurs. It is preferable to control. As described above, during this time, the internal pressure of the storage tank is often unstable, and the pressure reduction rate α is a desired rate (for example, a pressure reduction rate α corresponding to an extraction flow rate setting value Q ₀ described later). This is because it is usually slower than (value).

In this case, take-out flow rate setting means are provided for setting the desired extraction flow rate of the product gas, the allowable difference between the post-scaling has been the extraction flow rate set value Q ₀ and the pressure reduction rate α set by the extraction flow rate setting means is a predetermined It is preferable that an abnormality occurrence signal is input to the alarm means when the value is exceeded. Here, “scaling” means that the extracted flow rate setting value Q ₀ and the pressure decrease rate α are adjusted to a scale that can be compared. For example, there are a case where the pressure reduction rate α is converted into a flow rate, and a case where the extraction flow rate set value Q ₀ is converted into a pressure reduction rate.

  It is preferable that the operating conditions are not changed while the abnormality occurrence signal is input to the alarm means. The reason why the operating condition is changed when an abnormality occurs is that there is a possibility that the operation will be far from the desired control.

  The oxygen concentrator of the present invention can change various operating conditions such as the air delivery flow rate of the compressor in relation to the flow rate of the product gas actually taken out from the storage tank. As a result, not only can the power consumption and noise of the oxygen concentrator be reduced, but the oxygen concentrator can be operated under efficient operating conditions suitable for concentrating oxygen. In addition, the oxygen concentrator of the present invention is appropriately controlled even when there is an abnormality in the flow rate of the product gas actually taken out from the storage tank.

  Hereinafter, the oxygen concentrator of the present invention will be described in more detail with reference to the drawings. FIG. 1 is a schematic diagram showing an air circuit of the oxygen concentrator of the present invention. FIG. 2 is a schematic diagram showing the configuration of the control board. FIG. 3 is a schematic diagram showing changes in the internal pressure of the storage tank.

  FIG. 1 shows an example of the oxygen concentrator of the present invention. Adsorption chambers 10 and 11 in which an adsorbent that selectively adsorbs nitrogen in the air is stored, a compressor 40 that sends air to the adsorption chambers 10 and 11, and a product gas that is sent from the adsorption chambers 10 and 11 are temporarily And a storage tank 20 to be stored. The compressor 40 is provided with a cooling fan 50 for cooling it, and a gas flow path connecting the adsorption chambers 10 and 11 and the compressor 40 has an adsorption chamber pressure for detecting the internal pressure of the adsorption chambers 10 and 11. Detection means 31 is provided. The storage tank 20 is provided with a storage tank pressure detecting means 30 for detecting the internal pressure thereof, and an extraction for setting a desired extraction flow rate of the product gas is set in a gas flow path from which the product gas is extracted from the storage tank 20. A flow rate setting means 100 is provided. Each part of the oxygen concentrator is controlled by a control board 200 shown in FIG.

  Hereinafter, each part of the oxygen concentrator will be described. The adsorption chambers 10 and 11 contain an adsorbent that selectively adsorbs nitrogen. In the air sent from the compressor 40, nitrogen contained in the air is adsorbed by the adsorbent, and oxygen that has not been adsorbed by the adsorbent is concentrated and extracted. In this example, two adsorption chambers 10 and 11 are provided, but the present invention is not limited to this, and there may be three or four adsorption chambers. In the adsorption chambers 10 and 11, the nitrogen adsorption operation and the nitrogen desorption operation are alternately repeated. When the nitrogen adsorption operation is performed in one adsorption chamber, the nitrogen desorption operation is performed in the other adsorption chamber. For this reason, the oxygen concentrator as a whole has a structure that can efficiently perform a nitrogen adsorption operation. The shape and material of the adsorption chambers 10 and 11 are not particularly limited as long as they can withstand the pressure applied by the nitrogen adsorption operation, but in this example, a metal tank formed in a cylindrical shape is used. Also, the internal volume of the adsorption chambers 10 and 11 is not particularly limited, but is usually 0.3 to 2.0 liters, and in this example, 1.0 liters. Further, the adsorbent is not particularly limited as long as it selectively adsorbs nitrogen, but in this example, synthetic zeolite is used.

  The storage tank 20 temporarily stores oxygen-enriched gas sent alternately from the adsorption chambers 10 and 11 as product gas. The product gas stored in the storage tank 20 is supplied to the patient via the pressure reducing valve 80, the flow rate adjusting valve provided in the flow rate setting means 100, the check valve 72, and the humidifier 130. When the product gas is supplied from the adsorption chambers 10 and 11, the flow rate of the product gas supplied to the storage tank 20 exceeds the flow rate of the product gas taken out from the storage tank 20. The pressure increases. Further, when the product gas is not supplied from the adsorption chambers 10 and 11, the product gas stored in the storage tank 20 is being taken out, so the internal pressure of the storage tank 20 decreases. For this reason, as shown in FIG. 3, the internal pressure of the storage tank 20 changes while periodically increasing and decreasing. The shape and material of the storage tank 20 are not particularly limited as long as they can withstand the pressure applied by the internal product gas, but in this example, the storage tank 20 is made of a metal formed into a cylindrical shape similar to the adsorption chambers 10 and 11. A tank is used. The internal volume of the storage tank 20 is not particularly limited, but is usually 0.3 to 2.0 liters, and in this example, 0.5 liters.

The storage tank pressure detecting means 30 is not particularly limited as long as it is a pressure sensor capable of measuring the internal pressure of the storage tank 20 that periodically increases and decreases. The measurement pressure range required for the storage tank pressure detection means 50 varies depending on the internal volume of the storage tank 20, but is usually 0.3 to 2.0 kgf / cm ² . The adsorption chamber pressure detection means 31 is the same as the storage tank pressure detection means 30.

  The compressor 40 is one that can adjust the air delivery flow rate. In this example, a device capable of adjusting the air delivery flow rate by changing the rotation speed of the motor is used. The maximum air delivery flow rate required for the compressor 40 varies depending on the amount of adsorbent accommodated in the adsorption chambers 10 and 11 and nitrogen adsorption performance, but is usually 10 to 100 liters / min.

  The motor for driving the compressor 40 may be an AC type, but is preferably a DC type. Thereby, not only can the air delivery flow rate of the compressor 40 be easily changed by adjusting the driving voltage of the motor, but also the adsorption chambers 10 and 11 can be pressurized to a high pressure. . Among these, it is preferable to use a brushless motor. This is because the brushless motor has a long life and can be suitably used for a medical oxygen concentrator which is often driven for a long time. The driving voltage of the motor is usually controlled by an inverter. It is preferable that the output voltage of the inverter matches the driving voltage of the motor. This eliminates the need for a separate voltage conversion circuit. For example, if the motor drive voltage is DC140V and an inverter with an output voltage of DC140V is used, the inverter converts the power supply voltage (for example, commercial AC100V) to DC140V, and the motor is driven by the voltage output from the inverter. It can be driven directly. The power source of the oxygen concentrator is generally a commercial AC 100 V, but is not limited to this, and a car cigarette lighter or a fuel cell may be used. Thereby, it becomes possible to provide a portable oxygen concentrator, and an improvement in the patient's QOL (Quality of Life) can be expected.

  Moreover, it is preferable that the motor which drives the compressor 40 is provided with the motor rotational speed detection means which detects the rotational speed. As a result, the rotational speed of the motor can be feedback controlled. For this reason, when an abnormality occurs in the motor and the rotational speed deviates from a desired range, the abnormality can be detected. Furthermore, it is possible to control the rotation speed of the motor so as not to repeat increase and decrease more than necessary. The motor that drives the compressor 40 tends to repeat that the rotational speed gradually decreases and then increases again as the load increases as the air flow rate of the compressor increases. In this case, the noise generated from the motor changes in a short cycle and becomes annoying, but this noise can be suppressed.

Although the cooling fan 50 will not be specifically limited if it has the capability to cool the compressor 40, Usually, the thing with the largest airflow of 0.1-1.5 m < ³ > / min is selected. In order to save the power consumption of the cooling fan 50, a fan whose air volume (fan rotation speed) is variable is used.

Extraction flow rate setting means 100 is not particularly limited as long as the output can according to the extraction flow rate set value Q _0, which is set to, in this example, using what mounted potentiometer to flow adjustment valve Yes. The extraction flow rate setting unit 100, by turning the knob provided on the potentiometer are those capable of setting the take-out flow setpoint _{Q 0,} 0.25 liters /min,0.5 liters / min, Eight types can be set: 0.75 liter / min, 1 liter / min, 1.5 liter / min, 2 liter / min, 2.5 liter / min, and 3 liter / min. Extraction flow rate setting unit 100 outputs an electrical signal that varies for each extraction flow setpoint Q ₀ to the control board 200, a flow control valve. As the flow rate adjusting valve, a valve capable of adjusting the gas flow rate by changing the rotational position of the partition plate provided with a plurality of orifices having different diameters is used. The flow rate adjusting valve, the setting of the extraction flow rate set value Q ₀ is changed, the partition plate is rotated in conjunction therewith, so that the diameter of the orifice is switched. In this example, extraction flow setpoint Q ₀ which has been set, not only the control board 200, a flow control valve, but also output to the comparator circuit of the control board which will be described later, for this, the description of the comparator circuit I will mention it in detail.

Next, the control board 200 will be described. As shown in FIG. 2, the control board 200 includes a conversion circuit 201, a drive circuit 202, and a comparison circuit 203. The conversion circuit 201 receives the internal pressure data of the storage tank 20 from the storage tank pressure detecting means 30, calculates the pressure decrease rate α from the internal pressure data, and uses the obtained pressure decrease rate α as the product gas extraction flow rate Q _1. Convert to. Conversion to the calculation and product gas removal rate to Q ₁ pressure reduction rate α is usually carried out at the same time. Product gas removal flow Q ₁ which is converted by the conversion circuit 201 is equivalent to the flow rate of product gases that are actually retrieved from the storage tank, a reference value for controlling the oxygen concentrator. The product gas removal flow _{Q 1} is are outputted and the driver circuit 202 to the comparator circuit 203.

The algorithm for calculating the pressure decrease rate α (kgf / cm ² · s) from the internal pressure data of the storage tank 20 is not particularly limited as long as it calculates a decrease amount per predetermined time of the internal pressure of the storage tank 20. However, it is simple and preferable that the following formula (1) is used.
α = (P ₁ −P ₂ ) / ΔT ₂ (1)
Here, as shown in FIG. 3, P ₁ (kgf / cm ² ) has passed a predetermined time ΔT ₁ (sec) from time T ₀ (sec) when the internal pressure of the storage tank 20 reaches the maximum value P _max. P ₂ (kgf / cm ² ) is the internal pressure of the storage tank 20 at the moment when a predetermined time ΔT ₂ (sec) has passed. However, it is assumed that the internal pressure of the storage tank 20 does not reach the minimum value P _min between the time T ₀ (sec) and the time T ₀ + ΔT ₁ + ΔT ₂ (sec). The predetermined time ΔT ₁ is usually 0.1 to 2.0 seconds, and the predetermined time ΔT ₂ is usually 0.5 to 2.0 seconds.

Further, a conversion formula for obtaining the product gas extraction flow rate Q ₁ (liter / min) from the pressure decrease rate α (kgf / cm ² · s) is as shown in the following formula (2).
Q ₁ = (60 · V / P _a ) · α (2)
Here, P _a (kgf / cm ² ) is a standard atmospheric pressure (about 1.0 (kgf / cm ² )), and V is an internal volume (liter) of the storage tank 20. Thus, the flow rate of the product gas actually taken out from the storage tank 20 can be easily calculated from the pressure decrease rate α.

The comparison circuit 203 compares the product gas extraction flow rate Q ₁ received from the conversion circuit 201 with the extraction flow rate setting value Q ₀ received from the extraction flow rate setting means 100, and the difference exceeds a predetermined allowable value. In this case, the abnormality occurrence signal is output to the drive circuit 202 and the alarm means 210. As a result, when there is an abnormality in the actual product gas extraction flow rate, the occurrence of the abnormality can be detected. Comparator circuit 203 is the difference between the product gas removal rate Q _1, take-out flow rate set value Q ₀ may be one that outputs an abnormality occurrence signal when it exceeds the moment a predetermined allowable value, the product gas is the difference between the take-out flow rate Q _1, take-out flow rate set value Q ₀ is outputs continuously (e.g., several times or continuously for several minutes) abnormality signal when it exceeds a predetermined allowable value preferable. Thereby, it becomes possible to improve the reliability of the alarm issued from the alarm means 210 and to prevent malfunction of the oxygen concentrator. Moreover, it is preferable that the comparison circuit 203 does not output an abnormality occurrence signal until a predetermined time elapses after the oxygen concentrator is activated. Thereby, it becomes possible to prevent malfunction of the oxygen concentrator. The alarm means is not particularly limited as long as it generates an alarm by means that can be sensed by human senses such as light, sound, or vibration, but in this example, light is used.

Thus, when the product gas extraction flow rate Q ₁ is changed by the comparison circuit 203 comparing the product gas extraction flow rate Q ₁ with the extraction flow rate setting value Q ₀ , the change is the extraction flow rate setting value Q. It is possible to determine whether it is caused by a setting change of ₀ or a failure or malfunction of the oxygen concentrator. For example, if the product gas removal rate _{Q 1} is decreased to 3 L / min into a 2 liter / min, that the reduction is carried out setting change extraction flow setpoint _{Q 0} to 3 L / min into a 2 liter / min It is possible to determine whether it is caused by the above, or if the tube is crushed and closed, or if condensation occurs inside the tube. In this case, the decrease is to continue normal operation if it is determined to be due to configuration changes of the take-out flow setpoint Q _0, failure or if it is determined that a malfunction attributable to output an abnormality occurrence signal from the oxygen concentrator It is preferable to do. Thus, if the product gas removal rate Q ₁ is changed, it is possible to perform appropriate control. Here, the product gas removal rate Q ₁ is a case was described in which reduction, which is the same when the product gas removal rate Q ₁ is increased. Increase in the product gas removal flow Q ₁ is, in addition to the setting change of the take-out flow setpoint Q _0, may occur such as when the adjustment of the pressure reducing valve 80 is crazy.

Driving circuit 202, various operating conditions, and changed to correspond to the product gas removal rate Q ₁ received from the conversion circuit 201, it outputs a control signal according to the changed operating conditions to each part of the oxygen concentrator To do. Driving circuit 202 may be configured to change the various operating conditions each time the product gas removal rate Q ₁ is changed, but the product gas removal rate Q ₁ is continuously (e.g., several times or several minutes It is preferable that various operating conditions are changed when the values have changed to some extent from the previous values and have converged within a certain range. For example, the product gas removal rate _{Q 1} is, 1 L / min, then when the change 2 L / min, 1 liter / min, 1 l / min, it is determined 2 l / min and noise, does not change the various operating conditions, the product gas removal rate _{Q 1} is, 1 L / min, then when the change 2 L / min, 2 l / min, 2 l / min, the product gas extraction flow rate it is determined that Q ₁ is changed to a 2 liter / min, to change various operating conditions. Thereby, it becomes possible to improve the reliability of control of various operating conditions and prevent malfunction of the oxygen concentrator. The control signal output to each part of the oxygen concentrator may be an analog signal or a digital signal. Examples of the analog signal include those that continuously change the voltage and current, and examples of the digital signal include those that change the voltage and current in a pulse manner. In this example, the control signal is output to the compressor 40, the cooling fan 50, and the two-way valves 60 to 64, and the drive circuit 202 drives the rotation speed of the compressor 40, the driving voltage of the cooling fan 50, and the two-way valve 60. It is possible to control the switching timing of .about.64. For example, many products gas removal rate Q _1, if it is necessary to send a large amount of oxygen-enriched gas into the storage tank 20, it is possible such increase the rotational speed of the compressor 40. However, in this example, when the abnormality occurrence signal is input from the comparison circuit 203, the drive circuit 202 does not change the operation condition. In this case, the oxygen concentrator continues to operate under the operating conditions immediately before the abnormality occurrence signal is input.

The drive circuit 202 is preferably selected a set of operating conditions groups according to the product gas removal rate Q ₁ from the operating condition table, and outputs a control signal according to the operation condition group. Here, the operating condition group means a set of a plurality of operating conditions, and the operating condition table means a set of a plurality of sets of operating condition groups. Thereby, a plurality of operating conditions can be changed simultaneously and step by step, and the control of the oxygen concentrator can be further simplified. The operating condition table is not particularly limited as long as it consists of two or more operating condition groups, but preferably consists of 3 to 20 operating condition groups, more preferably 3 to 6 operating condition groups. Is preferred. In this example, as shown in Table 1, the operating condition table includes three sets of operating condition groups G _{1 to} G ₃ . In the operation condition groups G _{1 to} G ₃ , the compressor rotation speed, the suction chamber switching pressure (upper limit value P ₀ ), the cooling fan drive voltage, the upper pressure equalization time, and the lower pressure equalization time are set in advance. Operating conditions Group G ₃ are, which is selected when the product gas removal rate Q ₁ is larger, the operating condition group G _{1 is} intended to be selected when the product gas removal rate Q ₁ is small.

  Subsequently, the operation of the oxygen concentrator of the present invention will be described in 6 steps with reference to FIG. The oxygen concentrator of the present invention operates by repeating the following first to sixth steps. In the following, for convenience of explanation, it is assumed that a predetermined time has elapsed since the start of the oxygen concentrator, and immediately after the start of the first step, the internal pressure of the adsorption chamber 20 decreases to near atmospheric pressure. In addition, it is assumed that oxygen-enriched gas remains in the adsorption chamber 21.

In the first step, the adsorption chamber 10 is in the nitrogen adsorption process, and the adsorption chamber 11 is in the nitrogen desorption process. At this time, the valve 60 and the valve 63 are open, and the valve 61, the valve 62, and the valve 64 are closed. After the air compressed by the compressor 40 is sent to the adsorption chamber 10 through the valve 60, nitrogen is adsorbed by the adsorbent accommodated in the adsorption chamber 10, and oxygen that has not been adsorbed is concentrated. The oxygen-enriched air (oxygen-enriched gas) is sent to the storage tank 20 through the check valve 70 when the internal pressure of the adsorption chamber 10 becomes higher than the internal pressure of the storage tank 20. The oxygen-enriched gas is temporarily stored as a product gas in the storage tank 20 and then supplied to the patient. At this time, the gas remaining inside the adsorption chamber 11 is discharged to the atmosphere through the valve 63 together with the nitrogen adsorbed by the adsorbent. For this reason, the adsorbent accommodated in the adsorption chamber 11 can adsorb nitrogen again. The internal pressure of the adsorption chamber 11 decreases to near atmospheric pressure. Thereafter, when the internal pressure of the adsorption chamber 10 detected by the adsorption chamber pressure detection means 31 reaches the upper limit P ₀ , the valve 64 is opened, and the upper pressure equalization operation between the adsorption chamber 10 and the adsorption chamber 11 is started. The process proceeds to the second step.

In the second step, upper pressure equalization operation of the adsorption chamber 10 and the adsorption chamber 11 is performed. At this time, the valve 60, the valve 63, and the valve 64 are open, and the valve 61 and the valve 62 are closed. By this upper pressure equalization operation, the oxygen-enriched gas having a relatively high oxygen concentration remaining in the upper portion of the adsorption chamber 10 is transferred to the upper portion of the adsorption chamber 11 via the valve 64. For this reason, the adsorption chamber 11 can quickly send out the oxygen-enriched gas to the storage tank 20 when the fourth step of the nitrogen adsorption process is started. In this upper pressure equalization operation, the valve 63 may be closed. However, when it is desired to transfer a large amount of oxygen-enriched gas remaining in the upper portion of the adsorption chamber 10 to the upper portion of the adsorption chamber 11, the valve 63 is used. Opening is advantageous because the increase in the internal pressure of the adsorption chamber 11 is small. Thereafter, when a predetermined time [Delta] T ₃ has passed, at the same time the valve 63 is closed when the valve 62 is opened, the lower average pressure operation of the suction chamber 11 and the suction chamber 10 is started, the process proceeds to the third step.

In the third step, the lower pressure equalization operation of the adsorption chamber 10 and the adsorption chamber 11 is performed. The upper pressure equalizing operation is also continued. At this time, the valve 60, the valve 62, and the valve 64 are open, and the valve 61 and the valve 63 are closed. By this lower pressure equalizing operation, the oxygen-enriched gas whose oxygen concentration remaining in the lower portion of the adsorption chamber 10 is relatively close to air is transferred to the lower portion of the adsorption chamber 11 through the valve 60 and the valve 62. For this reason, the nitrogen adsorption process of the fourth step can be started in a state where the internal pressure of the adsorption chamber 11 is increased in advance, and the air delivery flow rate of the compressor 40 can be reduced. Thereafter, when a predetermined time ΔT ₄ elapses, the valve 61 is opened and the valve 60 and the valve 64 are closed simultaneously, and the upper pressure equalization operation and the lower pressure equalization operation of the adsorption chamber 10 and the adsorption chamber 11 are finished simultaneously. The nitrogen adsorption process in the adsorption chamber 11 is started, and the process proceeds to the fourth step.

In the fourth step, the adsorption chamber 10 is in the nitrogen desorption process, and the adsorption chamber 11 is in the nitrogen adsorption process. At this time, the valve 61 and the valve 62 are open, and the valve 60, the valve 63, and the valve 64 are closed. After the air compressed by the compressor 40 is sent to the adsorption chamber 11 through the valve 62, nitrogen is adsorbed by the adsorbent accommodated in the adsorption chamber 11, and oxygen that has not been adsorbed is concentrated. Air enriched with oxygen (oxygen-enriched gas) is sent to the storage tank 20 via the check valve 71. At the same time, the gas remaining in the adsorption chamber 10 is discharged to the atmosphere through the valve 61 together with the nitrogen adsorbed by the adsorbent. Other details are the same as those described in the first step. Thereafter, when the internal pressure of the adsorption chamber 11 detected by the adsorption chamber pressure detection means 31 reaches the upper limit P ₀ , the valve 64 is opened and the upper pressure equalization operation between the adsorption chamber 10 and the adsorption chamber 11 is started. The process proceeds to the fifth step.

In the fifth step, the upper pressure equalization operation of the adsorption chamber 10 and the adsorption chamber 11 is performed. At this time, the valve 61, the valve 62, and the valve 64 are open, and the valve 60 and the valve 63 are closed. By this upper pressure equalization operation, the gas having a relatively high oxygen concentration remaining in the upper portion of the adsorption chamber 11 is transferred to the upper portion of the adsorption chamber 10 via the valve 64. In this upper pressure equalizing operation, it is advantageous that the valve 61 is opened as in the case of the valve 63 in the second step, and the other details are the same as those described in the second step. Thereafter, when a predetermined time [Delta] T ₃ has passed, at the same time the valve 61 is closed when the valve 60 is opened, the lower average pressure operation of the suction chamber 11 and the suction chamber 10 is started, the process proceeds to the sixth step.

In the sixth step, the lower pressure equalization operation of the adsorption chamber 10 and the adsorption chamber 11 is performed. The upper pressure equalizing operation is also continued. At this time, the valve 60, the valve 62, and the valve 64 are open, and the valve 61 and the valve 63 are closed. By this lower pressure equalization operation, the gas whose oxygen concentration remaining in the lower portion of the adsorption chamber 11 is relatively close to air is transferred to the lower portion of the adsorption chamber 10 via the valve 62 and the valve 60. Other details are the same as those described in the third step. Thereafter, when a predetermined time ΔT ₄ elapses, the valve 63 is opened and the valve 62 and the valve 64 are closed simultaneously, and the upper pressure equalization operation and the lower pressure equalization operation of the adsorption chamber 10 and the adsorption chamber 11 are finished simultaneously. The nitrogen adsorption process of the adsorption chamber 10 is started, and the process proceeds to the first step again.

  In the first step to the sixth step, the air delivery flow rate of the compressor 40 is changed more as the pressure reduction rate α is faster, and is changed less as the pressure reduction rate α is slower. In the first step to the sixth step, the rotation speed of the cooling fan 50 is changed faster as the pressure reduction speed α becomes faster, and changed slower as the pressure reduction speed α becomes slower. Thereby, it is possible to reduce the power consumption and noise of the oxygen concentrator.

Further, in the first step and the fourth step, the upper limit value P ₀ is changed to be higher as the pressure decrease rate α becomes faster and is changed to be lower as the pressure decrease rate α becomes slower. This makes it possible to concentrate oxygen at an efficient pressure suitable for the actual product gas extraction flow rate. Furthermore, in the second step and the fifth step, the time ΔT ₃ (upper pressure equalization time) is changed longer as the pressure decrease rate α becomes faster and shorter as the pressure decrease rate α becomes slower. In the sixth step, the time ΔT ₄ (lower pressure equalization time) is changed longer as the pressure decrease rate α becomes faster and shorter as the pressure decrease rate α becomes slower. As a result, it is possible to concentrate oxygen by adopting an efficient equalization time suitable for the actual product gas extraction flow rate.

  Although the oxygen concentrator of the present invention can be used in various fields, it is particularly suitable as a medical oxygen concentrator used for the treatment of patients suffering from respiratory diseases such as asthma and bronchitis. It is. In particular, it can be suitably used as a small one used for home medical care.

It is the schematic diagram which showed the air circuit of the oxygen concentration apparatus of this invention. It is the schematic diagram which showed the structure of the control board. It is the schematic diagram which showed the change of the internal pressure of a storage tank.

Explanation of symbols

10, 11 Adsorption chamber
DESCRIPTION OF SYMBOLS 20 Storage tank 30 Storage tank pressure detection means 31 Adsorption chamber pressure detection means 40 Compressor 50 Cooling fan 60-64 Two-way valve
70 to 72 Check valve 80 Pressure reducing valve 90 Orifice 100 Extraction flow rate setting means 110 Suction filter 120 Silencer 130 Humidifier 200 Control board 201 Conversion circuit 202 Drive circuit 203 Comparison circuit 210 Alarm means

Claims (11)

A plurality of adsorption chambers containing an adsorbent that selectively adsorbs nitrogen in the air, a compressor for sending air to the adsorption chamber, and a storage tank for temporarily storing product gas sent from the adsorption chamber; In the pressure fluctuation adsorption type oxygen concentrator equipped with
A storage tank pressure detecting means for detecting the internal pressure of the storage tank is provided,
The internal pressure P ₁ of the storage tank at the moment when the predetermined time ΔT ₁ has elapsed from the time T ₀ when the internal pressure of the storage tank reaches the maximum value P _max , and then the predetermined time ΔT ₂ (however, the internal pressure of the storage tank is The minimum value P _min does not become between the time T ₀ and the time T ₀ + ΔT ₁ + ΔT ₂ ). The difference P ₁ -P ₂ from the internal pressure P ₂ of the storage tank at the moment when the time elapses By dividing by the time ΔT ₂ , the pressure reduction rate α (= (P ₁ −P ₂ ) / ΔT ₂ ) is calculated, and as the pressure reduction rate α becomes faster, the air delivery flow rate of the compressor automatically increases. It is changed to, as the pressure reduction rate α becomes slow, oxygen concentrator, wherein automatically Rukoto been changed to an air delivery rate of the compressor is reduced. Further, a cooling fan is provided for cooling the compressor, the rotation speed of the cooling fan is changed rapidly as the pressure reduction rate α is increased, according to claim 1, wherein the pressure reduction rate α is changed slowly as slower Oxygen concentrator. Furthermore, provided the suction chamber pressure detecting means for detecting the internal pressure of the adsorption chamber, where the internal pressure of the adsorption chamber detected by the suction chamber pressure detecting means reaches the upper limit value P _0, the average pressure operation of the suction chamber The oxygen concentrator according to claim 1 or 2, which is started. The oxygen concentrator according to claim 3 , wherein the upper limit value P ₀ is changed to be higher as the pressure reduction rate α becomes higher and changed to be lower as the pressure reduction rate α becomes slower. Time for equalizing pressure operation of the suction chamber is changed increases as the pressure decreases the rate α is increased, the oxygen concentrator according to any one of claims 1-4 in which the pressure reduction rate α is changed shorter as slow. Multiple sets of operating condition groups consisting of at least two operating conditions selected from compressor air delivery flow rate, adsorption chamber switching pressure, cooling fan rotation speed, upper pressure equalization time width or lower pressure equalization time width The oxygen concentrator according to any one of claims 1 to 5, wherein a set of operation condition groups corresponding to the pressure reduction rate α is selected from the operation condition table . Variable valve capable of adjusting the gas flow rate continuously is provided in the gas passage for taking out the product gas from the storage tank, the opening degree of the variable valve, either Claim 1-6 which is finely adjusted in accordance with the pressure decrease rate α Or an oxygen concentrator. During the period from when the oxygen concentrator is started until the predetermined time elapses, the air delivery flow rate of the compressor, the switching pressure of the adsorption chamber, the rotation speed of the cooling fan, the time width of the upper pressure equalization, and the time width of the lower pressure equalization The oxygen concentrator according to any one of claims 1 to 7, which is not changed. 9. The oxygen generator according to claim 1 , further comprising alarm means for issuing an alarm when an abnormality occurrence signal is inputted , and an abnormality occurrence signal is inputted to the alarm means when an abnormality in the pressure decrease rate α is detected. Concentrator. Furthermore, take-out flow rate setting means are provided for setting the desired extraction flow rate of the product gas, the difference between the post-scaling has been the extraction flow rate set value Q ₀ and the pressure reduction rate α set by the extraction flow rate setting means is a predetermined tolerance 10. The oxygen concentrator according to claim 9 , wherein an abnormality occurrence signal is input to the alarm means when the value exceeds. The air discharge flow rate of the compressor, the switching pressure of the adsorption chamber, the rotation speed of the cooling fan, the time width of the upper pressure equalization, and the time width of the lower pressure equalization are not changed while the abnormality occurrence signal is input to the alarm means. The oxygen concentrator according to 9 or 10 .

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