JP2002219176A - Oxygen concentrator for medical treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oxygen concentrator for medical treatment with which high quality concentrated oxygen gas (uniform oxygen concentration) for medical treatment can be provided under energy saving. SOLUTION: In an oxygen concentrator for medical treatment that provides concentrated oxygen gas (O2) by nitrogen gas (N2) to be absorbed to and desorbed from an absorbent with pressure swing absorbing method (PAS) with use of gained pressed air by a material air to be pressed using compressor, the oxygen concentrator for medical treatment is characterized in that the above oxygen concentrator for medical treatment has a revolution control unit that controls revolution of the compressor controls based on (1) an oxygen concentration sensor unit that detects an oxygen concentration produced and (2) the oxygen concentration detected at the oxygen concentration sensor unit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for producing concentrated oxygen gas, and more particularly to a medical oxygen concentrator for producing concentrated oxygen gas for medical or oxygen therapy from raw air.

More specifically, the present invention provides a compressor for compressing raw material air, which is an important component of this type of medical oxygen concentrator, and is obtained by a product gas (concentrated oxygen gas) concentration sensor. The present invention relates to a medical oxygen concentrator capable of controlling the operation of a compressor so as to reduce the power consumption while constantly maintaining a stable oxygen concentration using concentration information as a base for system control.

[0003]

2. Description of the Related Art Conventionally, oxygen therapy has been widely used for patients with chronic respiratory failure. For example, home oxygen therapy (Home Oxyg) for this kind of chronic respiratory disease
In en Therapy (HOT), a medical oxygen concentrator (hereinafter, sometimes simply referred to as an oxygen concentrator) is widely used as an important tool.

[0004] As the name implies, the medical oxygen concentrator applied to the home oxygen therapy (HOT) is used in a hospital or at home, and a fixed type or a movable type is widely used. It is used. Further, the oxygen concentrator is a method of producing a concentrated oxygen (O ₂ ) gas by treating a raw air (atmosphere) with an adsorbent such as zeolite to adsorb and remove nitrogen (N ₂ ) gas. Adsorption type oxygen concentrators are widely used.

[0005] The conventional adsorption-type oxygen concentrator using a sieve bed (adsorption cylinder) filled with an N ₂ adsorbent such as zeolite is an object to be improved by the present invention. The configuration of the conventional adsorption-type oxygen concentrator described above will be described in detail below with reference to FIG. 1 for describing the present invention.

In this type of adsorption type oxygen concentrator,
Zeolite, which is an adsorbent, is mainly composed of alumina and silicic acid, and has the property of selectively adsorbing nitrogen gas in air under high pressure and releasing the adsorbed nitrogen gas under low pressure. . This type of adsorbent has a property of adsorbing moisture in the air. For this reason, in order to produce high-concentration oxygen gas from the air, two adsorbers are used because the oxygen separation capacity is reduced by the adsorption of nitrogen and moisture under one adsorber. A method of producing a concentrated oxygen gas while efficiently adsorbing and desorbing nitrogen by switching between high pressure and low pressure is adopted. That is, when one sieve bed (adsorption cylinder) is pressurized and adsorbs nitrogen gas, the other sieve bed is depressurized to flush a desired purge gas (for example, a part of the generated concentrated oxygen gas). A device of a type that efficiently produces concentrated oxygen gas by alternately performing the same switching so that nitrogen gas is released is widely used.

Pressurization and depressurization are repeated using a sieve bed (adsorption cylinder) filled with zeolite as described above to continuously produce high-concentration oxygen gas by a PSA method (Press).
ure swing adsorption method, pressure swing type or pressure fluctuation type adsorption method).

FIG. 1 is a view for explaining an oxygen concentrator according to the present invention. The oxygen concentrator incorporating the conventional PSA method (pressure fluctuation adsorption method) described above with reference to FIG. Will be described.

As shown in FIG. 1, a schematic configuration of an oxygen concentrator incorporating a conventional PSA method (pressure fluctuation adsorption method) is composed of a concentrated oxygen gas generating section (manufacturing section) and an obtained concentrated oxygen gas. It is composed of a concentrated oxygen supply unit for supplying gas to patients and the like. The generation section (production section) of the above-described concentrated oxygen gas includes: 1. Pretreatment section for raw material air (AIR) 2. a sieve bed section composed of two sieve beds (adsorption cylinders) (A, B); N ₂ adsorption (concentration O) of _two sieve beds (adsorption column)
_3. Electromagnetic valves (SV1, SV2,..., And C) for switching between N ₂ generation and N ₂ purge (recovery of O ₂ generation capability). Product tank (storage for concentrated oxygen gas) (D).

The above-mentioned raw material air (AIR) pre-processing section pre-processes raw material air having a predetermined relative environmental temperature (RH). As shown in FIG. It comprises a compressor (2), a heat exchanger (3), a cooling fan (31), a HEPA filter (4) and the like. The HEPA filter is for preventing dust, bacteria, and the like contained in the raw air (AIR) from entering the sieve bed (adsorption cylinder) portions (A, B).

A sieve bed (adsorption cylinder) section (A, B) filled with zeolite is composed of an adsorption cylinder (for example, A) for selectively adsorbing nitrogen gas in air under high pressure and a nitrogen adsorbing under low pressure. And a desorption cylinder (regeneration purge tower) for releasing gas (for example, B). The two adsorption tubes (A, B) are switched after a predetermined time, so that the concentrated oxygen gas is efficiently produced.

The switching between the high pressure and the low pressure of the sheave beds (A, B) is performed by a solenoid valve (SV1, SV2,...) Under a control command from a predetermined control unit as shown in the figure.
…). FIG. 1 shows a piping configuration of the electromagnetic valve section with respect to the sheave bed section (A, B) in relation to switching between high pressure and low pressure, including a purge orifice (a), a switching valve (SV3), and a check valve (b). ) Are shown. In FIG. 1, a pipe section (C) disposed in the solenoid valve section indicates an exhaust muffler for N ₂ gas purged from an adsorption cylinder (for example, B) during regeneration purging.

The sieve bed (adsorption cylinder) section (A, B)
Is stored in the product tank (D). Next, the manufactured concentrated oxygen gas is adjusted to a desired flow rate and pressure in a predetermined flow rate / pressure adjusting section under the control of a predetermined control unit or other control means, and the concentrated oxygen gas is supplied to a patient or the like. Is done.

[0014]

As described above, for example, the basic principle of an oxygen concentrator for home medical use is a pressure fluctuation adsorption method or a pressure swing adsorption method (Presure S).
wing Adsorption (PAS method).
As the adsorbent, N ₂ molecules and O ₂
Zeolites having a large difference in the adsorption capacity for molecules are generally employed.

In the above-mentioned zeolite-based adsorbent, the adsorbing power for moisture tends to be stronger than the adsorbing power for nitrogen, and the amount of nitrogen adsorbed varies depending on the amount of water in compressed air supplied to the adsorbent. Oxygen recovery will be greatly affected.

The concentration of oxygen produced is such that if a large amount of adsorbent having high separation performance is used and the height of the adsorbent layer is increased, a product gas having high oxygen concentration (enriched oxygen gas) can be obtained. However, the supply amount (air volume) of the raw material air greatly affects the purity of the product gas. For this reason, in the prior art, it is considered that in order to obtain a predetermined product gas (enriched O ₂ gas or flow rate), it is absolutely necessary to secure a large amount of raw material air. The system design of the oxygen concentrator has been made under this.

In the prior art, as the system control of the oxygen concentrator, the "concentration" of the product gas (concentrated oxygen gas) is used.
There is no method for monitoring the amount of raw material air by monitoring the amount of air. For this reason, in the prior art, an approach is taken in which a change in the amount of raw material air and a change in the adsorption capacity of the adsorbent are anticipated in advance and the amount of raw material air is set with a large margin.

The present invention solves the above-mentioned drawbacks of the prior art and uses the "concentration" of the product gas (enriched oxygen gas) as a control base, while maintaining a stable oxygen concentration at all times. An object of the present invention is to provide a medical oxygen concentrator capable of always producing a concentrated oxygen gas having a stable oxygen concentration while eliminating a large amount of energy consumption during operation.

According to the present invention, the approach of giving a large margin to the capacity of the compressor (compressor) in consideration of the fluctuation factors of the raw air amount and the adsorbing capacity of the adsorbent in the prior art is eliminated. For example, there is provided a medical oxygen concentrator capable of always producing a concentrated oxygen gas having a stable oxygen concentration while eliminating a large amount of energy consumption in the operation of a compressor.

[0020]

SUMMARY OF THE INVENTION The present invention is summarized as follows. In the present invention, raw material air is compressed by a compressor, and nitrogen gas (N2) is compressed by a compression swing adsorption method (PAS) using the obtained compressed air. ₂ ) In a medical oxygen concentrator for producing a concentrated oxygen gas (O ₂ ) by adsorbing and desorbing the adsorbent on the adsorbent, the medical oxygen concentrator comprises: An oxygen concentration sensor unit to detect, and (2) a rotational speed control unit of a compressor that controls a rotational speed of the compressor based on the oxygen concentration detected by the oxygen concentration sensor unit,
The present invention relates to a medical oxygen concentrator characterized by having:

Hereinafter, the technical configuration and embodiments of the present invention will be described in detail with reference to the drawings. It goes without saying that the present invention is not limited to the illustrated one.

In the medical oxygen concentrator according to the present invention, as described in the description of the above-mentioned [Prior Art], in the prior art, the product control of the product gas (concentrated oxygen gas) is performed as the system control of the oxygen concentrator. Concentration "is monitored and the raw material air (AI
R) It is an attempt to remedy the drawbacks resulting from not employing a method for controlling the amount.

In the prior art, the raw material air amount is set with a large margin in consideration of the fluctuation factor of the oxygen concentration in the product gas, that is, the fluctuation factor of the raw material air amount, and the fluctuation factor of the adsorption capacity of the adsorbent. I needed to. For this reason, in the related art, it is not possible to always maintain a stable oxygen concentration of the product gas, and it is not possible to reduce the energy consumption of the compression energy of the raw material air in the compressor.

Here, a description will be given of a factor of variation of the amount of raw material air and a factor of variation of the adsorption capacity of the adsorbent.

First, there are the following factors as fluctuation factors of the raw material air amount. (1). Seasonal changes in temperature and humidity Under the weather conditions in Japan, differences in temperature and relative humidity and changes in relative humidity are large throughout the year. Therefore, the density of air changes due to the difference in temperature and humidity, and the capacity (air volume) of the compressor also changes. (2). Differences in temperature and humidity between regions: Japan is a long island nation from north to south, so there are differences in temperature and relative humidity between regions.
For this reason, the above can be said to depend on the region. (3). Difference in altitude: Oxygen concentrators are used even from zero meters above sea level to 2,000 m or more above sea level. For this reason, the density of air changes with the difference in altitude, and a great difference occurs in the capacity (air volume) of the compressor. (4) Power supply conditions: Oxygen concentrators are sometimes used in environments where the power supply is not very good. Therefore, when the voltage decreases, the capacity (air volume) of the compressor also decreases. (5) Difference in power supply frequency: The capacity (air volume) of the compressor is reduced by about 20% at 50 Hz as compared with 60 Hz.

Next, the causes of the change in the adsorption capacity of the adsorbent are as follows. (1). Change in temperature and humidity: The amount of moisture in the compressed air changes due to the difference in temperature and humidity, the amount of nitrogen adsorbed changes, and the oxygen recovery rate and the concentration (quality) of the product gas (enriched oxygen gas) change. I do. (2) Deterioration of the adsorbent: The adsorbent gradually deteriorates in the long term, and the adsorption performance decreases. Therefore, the product gas (concentrated oxygen gas) recovery rate (generation rate) and concentration (quality) change.

The present invention has been made to solve the above-mentioned drawbacks of the prior art, and the above-mentioned drawbacks are obtained by using the "concentration" of the product gas (concentrated oxygen gas) in the system of the oxygen concentrator as the basis for system control. Is to eliminate.

In the present invention, the above-mentioned fluctuation factors (fluctuation factors in the amount of raw material air, fluctuation factors in the adsorbing capacity of the adsorbent) are obtained by giving a large margin to the capacity of the conventional compressor (compressor) by the concentration-based system control. ) Can be converted to a low power consumption type system.

Also, under the concentration-based system control of the present invention, the instruction to switch between adsorption and desorption in the adsorption column can also save energy. This is for the following reason. As is well known, there are the following two types of instructions for switching between adsorption and desorption in the adsorption column. (1). Pressure control method: A method that detects the pressure in the product tank and switches the adsorption / desorption mode when the set pressure (circuit pressure) is reached. In this case, when the capacity of the compressor changes, the cycle time changes. (2). Time control method: A method that sets the cycle time and switches the adsorption / desorption mode when the set time (cycle time) is reached. In this case, when the capacity of the compressor changes, the circuit pressure changes.

According to the concentration-based system control of the present invention, the set flow rate is made to correspond to the rotation speed under a predetermined rotation speed of the compressor which is a condition for keeping the concentration constant. Alternatively, a cycle time is set. In this regard, in the prior art, since the circuit pressure or the cycle time is set based on the performance at the time of setting the maximum flow rate, the oxygen concentrator is operated at an unnecessarily high pressure even when using the low flow rate of the oxygen concentrator. That wastes energy.

Another advantage of the concentration-based system control of the present invention is that high performance adsorbents can be used economically and appropriately. In this regard, in the prior art, there is a tendency to use a large amount of a high-performance adsorbent. In addition, waste of energy based on the difference in the power supply frequency (50 Hz, 60 Hz) of the compressor can be eliminated by the concentration-based system control.

As described above, the medical oxygen concentrator of the present invention has the greatest feature in that system control is based on concentration. The medical oxygen concentrator incorporating the concentration-based system control of the present invention detects the concentration of product gas (concentrated oxygen gas) generated in the adsorption column and transferred from the product tank to the supply unit, and the detection result is obtained. The control unit (rotation speed control unit of the compressor) for controlling the rotation speed of the compressor (compressor) based on the above is configured as an essential component.

In the present invention, the above-mentioned compressor rotation speed control unit performs the following steps based on the detected concentration information of the concentration sensor for detecting the oxygen concentration of the concentrated oxygen gas (product gas). In such a case, the rotation speed of the compressor (compressor) is maintained at the rotation speed (including a desired upper and lower allowable range; the same applies hereinafter). (2). (3) It is configured to have at least a function of decreasing the number of revolutions of the (compressor), and (3) increasing the number of revolutions of the compressor (compressor) when the oxygen concentration falls below the predetermined oxygen concentration.

The reference oxygen concentration is, for example,
In the PAS method, argon (Ar) gas is also concentrated together with oxygen, so the upper limit of the oxygen concentration is said to be 95.4%, and a concentration slightly lower than the upper limit may be set as the set concentration. In the present invention, a zirconia oxygen sensor, for example, may be used as the concentration sensor for detecting the oxygen concentration. Further, in the present invention, the raw material air (AI
R) is not particularly limited as long as it can receive a control command from the rotation speed control unit of the compressor and control the rotation speed, as a compressor for compressing R). Absent. As this type of compressor (compressor), a scroll compressor used in a general respirator or the like may be used.

In the medical oxygen concentrator according to the present invention, the system control section is essentially constituted by the above-mentioned concentration sensor and the rotational speed control section of the compressor (compressor), but has other system control functions. Needless to say, it may be held. For example, in the system controller, (1) a function of arranging a flow setting device for setting the flow rate of the concentrated oxygen gas to the supply side and storing the number of rotations of the compressor for each set flow rate, (2) setting. (3) A function to set the circuit pressure or cycle time for instructing switching between adsorption and desorption in the adsorption cylinder according to the set flow rate. , (4). A pressure setting device for detecting the circuit pressure of the product tank (concentrated oxygen gas) is installed,
Needless to say, the function of storing the circuit pressure obtained from the pressure setting device may be held.

In the present invention, the system control unit for realizing the additional control function described above and the rotational speed control unit for the compressor may be combined (integrated) or may be separated and independent. Needless to say.

Hereinafter, the medical oxygen concentrator according to the present invention, particularly, a mechanism for controlling the number of revolutions of the compressor will be described with reference to the drawings.

FIG. 1 is a block diagram schematically showing a medical oxygen concentrator according to the present invention. In particular, since FIG. 1 illustrates the control function of the control (control unit), it can be called a control system diagram. In FIG. 1, raw material air (AI
R)-The elements of the product tank (D) are the same as those of the above [Prior art]
Since it was explained in the section, the description is omitted.

In FIG. 1, (1) .1.5 is a pressure setting device for measuring the pressure of the product gas (enriched oxygen gas), and (2) .1.6 is a concentration sensor for measuring the oxygen concentration of the product gas (enriched oxygen gas). ,
(3) .7 is a flow setting device for measuring the flow rate of product gas (enriched oxygen gas), (4) .8 is an enriched oxygen supply section for supplying enriched oxygen gas to the user, and (5) .E is a control section. (System control unit), (6) .F especially shows a compressor rotation speed control unit for controlling the rotation speed of the compressor. In the present invention,
The E and F may be integrated (coupled).

In FIG. 1, (1) .51 is a piping for detecting the circuit pressure of the product tank (D) obtained by the pressure setting device (5) with the pressure sensor of the control section (E). ) .61 is a wiring for transmitting the density information obtained from the density sensor (6) to the control unit (E), (3) .71
The wiring for transmitting the flow information obtained from the flow rate setting device (7) to the control unit (E), (4) .F _1, the rotation speed control of the compressor rotation speed control signal (F) the compressor ( 2) shows wiring to be transmitted.

The function of each element (each member) in FIG. 1 is clear from the above-described explanation and the explanation terms in the figure, so that a more detailed explanation is omitted.

FIG. 2 illustrates in particular the control functions of the control section (E) and of the rotational speed control section (F) (of the compressor). In the figure, “a%” indicates the maximum allowable oxygen concentration, and “b%” indicates the minimum allowable oxygen concentration.

FIGS. 3 and 4 show the operation of each solenoid valve (valve) (SV1 to SV5) and the pressure of each part under the operation of the compressor (2) at a predetermined rotation speed. It is illustrated. FIG. 3 is a diagram equivalent to the corresponding part of FIG.

In FIG. 4, when the pressure in the product tank reaches the set pressure, the valves SV1, SV4, SV2, and SV5 are reversed, and the adsorption cylinder A is changed from the adsorption mode to the desorption mode, and the adsorption cylinder B is changed to the desorption mode. To the adsorption mode. The SV3 is turned on for a predetermined time before and after the timing of mode switching, and plays a role of increasing the efficiency of the suction mode.

Next, in the medical oxygen concentrator according to the present invention, the pressure of the product tank, that is, the circuit pressure is controlled based on the set flow rate set under the predetermined number of revolutions of the compressor (compressor). The advantages (merits) of (setting) will be described. Table 1 below shows the “set flow rate” (liter / min) and set pressure (circuit pressure).
An example of the data of the oxygen concentration of the concentrated oxygen gas produced under the relationship of (kg · f / cm ² ) is shown.

[0046]

[Table 1]

Table 1 shows the following. (1) At the maximum flow rate (3 liter / min), the oxygen concentration is high under high circuit pressure. (2) At low flow rates (eg, 0.25 l / min), the oxygen concentration is high under low circuit pressure. From this, it is understood that setting the circuit pressure for each set flow rate is extremely important from the viewpoint of energy saving and production of high-quality concentrated oxygen gas. It goes without saying that setting the cycle time for each set flow rate also has the same effect.

[0048]

The medical oxygen concentrator according to the present invention employs a control base for system control, which is not employed at all in the prior art, that is, the system for controlling the oxygen concentration of the product gas (concentrated oxygen gas). There is the biggest feature point in the control base point. And the present invention
Based on the oxygen concentration information of the product gas (enriched oxygen gas),
The system that controls the optimal rotation speed of the compressor that compresses the raw air is adopted.

According to the control method of the above-mentioned system of the present invention, it is possible to produce a concentrated oxygen gas (with a constant oxygen concentration) of stable quality while saving energy.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of a medical oxygen concentrator according to the present invention.

FIG. 2 is a diagram illustrating an operation of a control unit of the medical oxygen concentrator according to the present invention.

FIG. 3 is a diagram illustrating the operation of a solenoid valve (valve) of the medical oxygen concentrator according to the present invention.

FIG. 4 is a view for explaining pressures at various parts detected under the operation of the solenoid valve (valve) shown in FIG. 3;

Claims (6)

[Claims] 1. A raw material air is compressed by a compressor, and a nitrogen gas (N ₂ ) is adsorbed and desorbed to an adsorbent by a compression swing adsorption method (PAS) using the obtained compressed air to obtain a concentrated oxygen gas ( In a medical oxygen concentrator for producing O ₂ ),
The medical oxygen concentrator, (1) .Oxygen concentration sensor unit that detects the oxygen concentration of the manufactured concentrated oxygen gas, and (2) .Based on the oxygen concentration detected in the oxygen concentration sensor unit, A medical oxygen concentrator, comprising: a compressor rotation speed control unit that controls the rotation speed of the compressor. 2. The compressor rotation speed control section has at least 1) the current rotation speed of the compressor at a predetermined oxygen concentration as its control function, and 2). The medical oxygen concentrator according to claim 1, wherein the medical oxygen concentrator has a control function of: sometimes reducing the rotation speed of the compressor; and 3) increasing the rotation speed of the compressor when the oxygen concentration is equal to or lower than a predetermined oxygen concentration. . 3. The medical oxygen concentrator according to claim 1, further comprising a flow setting device for setting a flow rate of the manufactured concentrated oxygen gas, and a control unit for storing a rotational speed of the compressor for each flow rate setting. . 4. A flow rate setting device for setting a flow rate of the manufactured concentrated oxygen gas, and a control unit for instructing a switching of a mode of adsorption / desorption of nitrogen gas to / from an adsorbent according to the set flow rate. 4. The medical oxygen concentrator according to 3. 5. The medical device according to claim 4, wherein the switching of the adsorption / desorption mode of the nitrogen gas to the adsorbent is performed at a set pressure (circuit pressure) or a set cycle time (set time). Oxygen concentrator. 6. The medical oxygen concentrator according to claim 1, further comprising a pressure setting device for setting a pressure of the manufactured concentrated oxygen gas, and a control unit for storing a circuit pressure.