JPH0768120A - Oxygen enrich air forming device - Google Patents

Abstract

PURPOSE:To efficiently execute the enrichment of oxygen (the adsorption of nitrogen) and the adsorption of carbon dioxide with one adsorption tank. CONSTITUTION:A high pressure circuit 15 provided with an orifice 14 and a solenoid valve EV5 and a low pressure circuit 16 provided with a solenoid valve EV6 are provided in parallel at the outlet side of the adsorption tank 12. At the time of oxygen enriching mode, the pressure in the adsorption tank 12 is increased up to a pressure suitable for adsorbing nitrogen by passing air through the high pressure circuit 15 to increase the resistance of flow passage. On the other hand, at the time of carbon dioxide removing mode, the pressure in the adsorption tank 12 is decreased up to the pressure suitable for adsorbing carbon dioxide by passing air through a bypass flow-in passage 18, the adsorption tank 12 and a bypass flow-out passage 19 in this order so as to partially and limitedly use the adsorbent housing area in the tank 12 to decrease the pressure drop in the adsorption tank 12 and passing air through the low pressure circuit 16 to decrease the resistance of the flow passage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oxygen-enriched air generator for sending air into an adsorption tank containing an adsorbent for adsorbing nitrogen and carbon dioxide in the air to produce oxygen-enriched air. is there.

[0002]

2. Description of the Related Art In recent years, an oxygen-enriched air generator for removing oxygen in the air to produce oxygen-enriched air in order to prevent a decrease in the oxygen concentration in the room and maintain the comfort of a living space. Have been developed (JP-A-2-174913, JP-A-63-43814, JP-A-59-21263).
No. 2). The general structure of this oxygen-enriched air generator is to install an adsorption tank containing an adsorbent such as zeolite that adsorbs nitrogen in the air, and send air to the adsorption tank by a compressor to generate oxygen-enriched air. However, this oxygen-enriched air is blown out into the room.

[0003]

By the way, as an air environment that affects comfort, there is a carbon dioxide concentration in addition to an oxygen concentration. To confirm this, the relationship between the air environment (oxygen concentration, carbon dioxide concentration) and the human fatigue reduction rate was examined, and the results shown in FIG. 8 were obtained. In FIG. 8, the region I is a region where the fatigue reduction rate is high and the user feels comfortable due to the high oxygen concentration / low carbon dioxide concentration.
Is a region in which the oxygen concentration is slightly low, but the fatigue reduction rate (comfort) that is almost the same as in region I can be secured by reducing the carbon dioxide concentration. It is an area of low comfort.

As is clear from this relationship, even if the oxygen concentration is high, if the carbon dioxide concentration is high, the fatigue reduction rate (comfort) will be significantly reduced. Therefore, in order to maintain comfort, it is also necessary to lower the carbon dioxide concentration in addition to oxygen enrichment.

However, the above-mentioned conventional ones aim to improve the air environment only by enriching oxygen,
Since it is not configured to control the carbon dioxide concentration, sufficient comfort cannot be ensured. Incidentally, an adsorbent such as zeolite has an ability to adsorb carbon dioxide together with adsorption of nitrogen, but since carbon dioxide has a strong selective adsorption property as compared with nitrogen as described later, under the same conditions as adsorption of nitrogen, It is not possible to achieve both adsorption of nitrogen and adsorption of carbon dioxide, and adsorption of carbon dioxide cannot be performed efficiently.

The present invention has been made in consideration of such circumstances, and its purpose is to provide a single adsorption tank.
Oxygen that can efficiently perform oxygen enrichment (nitrogen adsorption) and carbon dioxide adsorption, can properly control both oxygen concentration and carbon dioxide concentration in the air, and can realize an extremely comfortable air environment It is to provide an enriched air generator.

[0007]

In order to achieve the above object, an oxygen-enriched air generator according to claim 1 of the present invention comprises:
An adsorption tank containing an adsorbent for adsorbing nitrogen and carbon dioxide in the air is provided, and in the adsorption tank, air is sent by an air feeding means to generate oxygen-enriched air,
By switching the flow path resistance of the air flow path on the outlet side of the adsorption tank, an oxygen enrichment mode for setting the pressure in the adsorption tank to a pressure suitable for adsorption of nitrogen and a pressure suitable for adsorption of carbon dioxide. The flow path resistance switching means for switching between the carbon dioxide removal mode to be set is provided.

In this case, as in claim 2, the carbon dioxide concentration detecting means for detecting the carbon dioxide concentration in the indoor air and the flow path resistance switching means when the detected carbon dioxide concentration exceeds a set value are provided. A control means for switching to the carbon dioxide removal mode and operating may be provided.

Further, in place of the flow path resistance switching means of claim 1, as in claim 3, an oxygen enrichment mode in which the flow of air in the adsorption tank is spread over the entire adsorbent accommodating region, and the adsorbent. A configuration may be provided in which a distribution mode switching unit is provided to switch between a carbon dioxide removal mode in which air is caused to flow so as to narrow an air circulation range in the accommodation region and a pressure loss in the adsorption tank is reduced.

Also in this case, as in claim 4,
A carbon dioxide concentration detecting means for detecting the carbon dioxide concentration in the indoor air, and a control means for operating the flow mode switching means by switching to the carbon dioxide removing mode when the detected carbon dioxide concentration exceeds a set value are provided. May be.

[0011]

[Operation] When the pressure in the adsorption tank (hereinafter referred to as "swing pressure") is reduced by reducing the flow path resistance of the air flow path on the outlet side of the adsorption tank, the flow rate of the air flowing in the adsorption tank increases. . However, due to the characteristics of the adsorbent (for example, zeolite), as shown in FIG. 6, the saturated adsorption amount of nitrogen and carbon dioxide decreases as the swing pressure decreases, so that the optimum swing pressure for nitrogen adsorption exists. A peak point appears in the oxygen enrichment amount. On the other hand, carbon dioxide has a stronger selective adsorption property to polar molecules of the adsorbent (for example, zeolite) than nitrogen, so that the adsorption amount of carbon dioxide per unit time increases as the air flow rate increases. There is.

Therefore, in the first aspect of the invention, at the time of oxygen enrichment (removal of nitrogen), the flow path resistance switching means switches the flow path resistance of the air flow path on the outlet side of the adsorption tank to the high pressure side to adjust the swing pressure. Set to a pressure suitable for nitrogen adsorption. As a result, nitrogen in the air is efficiently adsorbed and the oxygen concentration in the air is increased. On the other hand, when removing carbon dioxide, the flow path resistance switching means switches the flow path resistance of the air flow path on the outlet side of the adsorption tank to the low pressure side, and the swing pressure is set to a low pressure suitable for carbon dioxide adsorption. As a result, carbon dioxide in the air is efficiently adsorbed, and the carbon dioxide concentration in the air is reduced.

According to the third aspect of the invention, at the time of oxygen enrichment (removal of nitrogen), the flow mode switching means switches to an oxygen enrichment mode in which the air flow in the adsorption tank is spread over the entire adsorbent storage area. Thus, nitrogen in the air is efficiently adsorbed by using the entire adsorbent storage area. on the other hand,
At the time of removing carbon dioxide, the flow mode switching means switches to a carbon dioxide removing mode in which air is passed so as to narrow the air flow range in the adsorbent storage area, and the pressure loss in the adsorption tank is reduced. As a result, the swing pressure is reduced, the flow rate of air in the adsorption tank is increased, and carbon dioxide in the air is efficiently adsorbed.

By the way, there are four possible methods for switching between the oxygen enrichment mode and the carbon dioxide removal mode. It is switched by the user's own judgment by manual operation. Switch periodically by timer operation. Automatic operation is performed by detecting the oxygen concentration in indoor air. Automatic operation is performed by detecting the carbon dioxide concentration in indoor air. Further, a configuration in which these items are appropriately combined is also conceivable.

As described above, even if the oxygen concentration is high, if the carbon dioxide concentration is high, the fatigue reduction rate (comfort) will be significantly reduced. Therefore, in order to maintain comfort, it is also necessary to lower the carbon dioxide concentration in addition to oxygen enrichment. A closer examination of this relationship confirmed that the better the air quality (carbon dioxide concentration and oxygen concentration), the more the respiratory volume of the human body can be reduced.
This respiration rate is an index showing the metabolic rate of the human body, and it is considered that the magnitude of the metabolic rate affects not only physical fatigue but also mental fatigue. Therefore, suppressing an increase in metabolic rate (in this case, an increase in respiratory rate) is considered to be better air purification.

According to the results of experiments conducted by the present inventor, as shown in FIG. 13, it was confirmed that oxygen enrichment can reduce the respiration rate. However, as the carbon dioxide concentration increases, the respiration rate increases, It was confirmed that when the carbon dioxide concentration is high, the respiratory volume cannot be reduced to the level in the clean environment even if the oxygen is enriched. In this case, as shown in FIG. 14, it was also confirmed that lowering the carbon dioxide concentration was more effective in reducing the respiratory volume than oxygen enrichment.

Focusing on this relationship, the constitutions for realizing a more comfortable air quality are the constitutions of claims 2 and 4 of the present invention. This device is provided with a carbon dioxide concentration detecting means for detecting the carbon dioxide concentration in the indoor air, and when the carbon dioxide concentration detected by this carbon dioxide concentration detecting means exceeds a set value, the control means is The flow path resistance switching means or the flow mode switching means of claim 3 is switched to the carbon dioxide removal mode for operation. Thereby, the carbon dioxide concentration can be suppressed below the set value. Therefore, the respiration rate can be reduced more effectively than when the oxygen enrichment is continued while the carbon dioxide concentration is high, and the subsequent oxygen enrichment can be performed more effectively.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. The room air is sucked into the compressor 11, which is an air supply means, through the electromagnetic valve EV1. In the oxygen enrichment mode, the air discharged from the compressor 11 has two solenoid valves EV as shown by a solid arrow in FIG.
2, through EV3, from the first port P1 to adsorption tank 1
It flows into 2. In the adsorption tank 12, an adsorbent 1 such as zeolite that adsorbs nitrogen and carbon dioxide in the air 1
3 (see FIG. 2). The oxygen-enriched air that has passed through the adsorption tank 12 in the oxygen-enriched mode is, as shown by the solid arrow in FIG. 1, the second port P2 → the solenoid valve EV4.
→ Orifice 14 → Solenoid valve EV5 flows through the path and is blown out into the room. A low pressure circuit 16 having an electromagnetic valve EV6 is connected in parallel to the high pressure circuit 15 having the orifice 14 and the electromagnetic valve EV5, and the high pressure circuit 15 and the low pressure circuit 16 constitute a flow path resistance switching means 17. Has been done.

In this case, in the oxygen enrichment mode, by closing the solenoid valve EV6 of the low pressure circuit 16 and opening the solenoid valve EV5 of the high pressure circuit 15, the flow path resistance of the air flow passage on the outlet side of the adsorption tank 12 is increased. Is increased to switch the pressure (swing pressure) in the adsorption tank 12 to a pressure suitable for nitrogen adsorption (for example, 0.5 kgf / cm 2 G) (see FIGS. 6 and 7). On the other hand, in the carbon dioxide removal mode, by closing the electromagnetic valve EV5 of the high-pressure circuit 15 and opening the electromagnetic valve EV6 of the low-pressure circuit 16, the flow path resistance of the air circulation path on the outlet side of the adsorption tank 12 is reduced. Then, the swing pressure is set to a low pressure suitable for adsorption of carbon dioxide (for example, 0.08 kgf /
cm2 G) (see Figures 6 and 7). In this carbon dioxide removal mode, oxygen-enriched air flows through the low-pressure circuit 16 and is blown out into the room, as indicated by the one-dot chain line arrow in FIG.

On the other hand, the side wall of the adsorption tank 12 has a third port P3 which serves as an air inlet in the carbon dioxide removal mode.
Is provided, and the solenoid valve EV2 is connected to the third port P3.
Bypass inflow path 1 branched from the air flow path between EVs 3
8 is connected, and the solenoid valve E is also provided in the bypass inflow passage 18.
V7 is provided. As shown in FIG. 2, the tip of the bypass inflow path 18 is inserted into the adsorption tank 12 from the third port P3, and in the carbon dioxide removal mode,
The electromagnetic valve EV7 of the bypass inflow passage 18 is opened to discharge the air from the bypass inflow passage 18 toward the first port P1 side. The first port P1 serves as an air inlet in the oxygen enrichment mode, but serves as an air outlet in the carbon dioxide removal mode. The air flowing out from the first port P1 in the carbon dioxide removal mode is the air between the solenoid valve EV4 and the flow path resistance switching means 17 via the bypass outflow passage 19 as shown by the one-dot chain line arrow in FIG. It flows into the outflow passage 20, and then flows toward the flow path resistance switching means 17 side. The bypass outflow passage 1
An electromagnetic valve EV8 is also provided in the valve 9.

The bypass inflow path 18 and the bypass outflow path 19 described above constitute a flow mode switching means 21 for switching the air flow in the adsorption tank 12 from the oxygen enrichment mode to the carbon dioxide removal mode. In this case, in the oxygen enrichment mode, the electromagnetic valves EV7 and EV8 of both the bypass inflow passage 18 and the bypass outflow passage 19 are closed to allow air to flow from the first port P1 to the second port P2, and the adsorption tank Air is spread over the entire storage area of the adsorbent 13 in 12. On the other hand, in the carbon dioxide removal mode, the solenoid valves EV7 and EV8 of both the bypass inflow passage 18 and the bypass outflow passage 19 are opened to allow air to flow from the third port P3 to the first port P1 and the adsorption tank 1
The third port P3 of the storage area of the adsorbent 13 in
Air is made to flow using the portion between the first port P1 and the first port P1 (the hatched portion of the dotted line shown in FIG. 2).

In addition, a surge tank 22 is provided in the air outflow passage 20 in front of the passage resistance switching means 17. The surge tank 22 has the flow path resistance switching means 17 in the oxygen enrichment mode and the carbon dioxide removal mode.
Captures and stores part of the air flowing to the side. On the other hand, in the deaeration mode, the air stored in the surge tank 22 is the solenoid valve EV4 → second port P2 → adsorption tank 12 → first port P1 → as shown by the dotted arrow in FIG.
Electromagnetic valve EV3 → electromagnetic valve EV9 → compressor 11 → electromagnetic valve EV10 is discharged to the outside through a path. At this time, in the process of the air passing through the adsorbent 13 in the adsorption tank 12, the nitrogen molecules and carbon dioxide molecules adsorbed by the adsorbent 13 are removed to restore the adsorption capacity of the adsorbent 13. The pressure in the adsorption tank 12 in the degassing mode is set to be, for example, -0.8 kgf / cm2G. Solenoid valve EV1 to solenoid valve EV1 in each mode described above
Switching of 0 (open) / OFF (closed) of 0 is as shown in FIG.

Next, the configuration of the electric circuit of the control system will be described with reference to FIG. The first relay coil RL1 is connected to the power switch 25 in series. When the power switch 25 is turned on, the first relay coil RL1 is energized and the first relay switch RL1S is turned on. When the first relay switch RL1S is turned on, the oxygen sensor amplifier 27 starts to operate. This oxygen sensor amplifier 2
Reference numeral 7 is a third relay coil for executing the oxygen enrichment mode, which determines whether or not to execute the oxygen enrichment mode operation based on the output signal of an oxygen sensor (not shown) that detects the oxygen concentration in the room. Controls energization of RL3. The series circuit of the relay switch 26 and the second relay coil RL2 is connected in parallel to the series circuit of the oxygen sensor amplifier 27 and the third relay coil RL3. In this case, the oxygen concentration in the air detected by the oxygen sensor is, for example, 20.
When it is 0% or less, the relay switch 26 is kept off, but when the oxygen concentration exceeds 20.0%, the oxygen sensor amplifier 27 turns on the relay switch 26,
The second relay coil RL2 is energized.

When the second relay coil RL2 or the third relay coil RL3 is energized, the second relay switch RL2S or the third relay switch RL3S is turned on and the relay timer RLT starts the time counting operation. The operation of the carbon dioxide removal mode or the oxygen enrichment mode is executed. The relay timer RLT switches the on state of the relay switch RL2S or RL3S that has been turned on to the off state after, for example, 20 seconds, and ends the operation in the carbon dioxide removal mode or the oxygen enrichment mode. While the relay timer RLT is operating (that is, the relay switch RL2
While S or RL3S is on), the relay switch SW1 is maintained in the on state, the solenoid valves EV1 and EV2 are energized, and these are maintained in the open state.

The relay timer RLT keeps the relay switches SW2 and SW3 in the on state for, for example, 20 seconds after the oxygen enrichment mode or the carbon dioxide removal mode is finished (after the relay switch RL2S or RL3S is switched to the off state). Then, the solenoid valves EV3, EV4, EV9,
The EV 10 is energized, these are maintained in an open state, and the deaeration mode operation is executed for, for example, 20 seconds.

The flow of operation of the oxygen-enriched air generator configured as described above will be described with reference to the flow chart of FIG. First, in step 101, an oxygen sensor (not shown)
It is determined whether or not the oxygen concentration in the air detected by is less than 20.0%, and if YES (20.0% or less), it is necessary to increase the oxygen concentration in the air. After the transition, the third relay coil RL3 is energized, the third relay switch RL3S is turned on, and the operation in the oxygen enrichment mode is started.

In the oxygen enrichment mode, as shown in FIG. 3, the solenoid valves EV1 to EV5 are opened to remove the indoor air.
As indicated by the solid arrow in FIG. 1, the solenoid valve EV1 → the compressor 11 → the solenoid valve EV2 → the solenoid valve EV3 → the first port P1 → the adsorption tank 12 → the second port P2 → the solenoid valve EV
4 → high pressure circuit 15 (orifice 14 → solenoid valve EV5) →
The oxygen concentration in the indoor air is increased by circulating it in the indoor path. At this time, the oxygen-enriched air is caused to flow through the high-pressure circuit 15 (orifice 14 → electromagnetic valve EV5) to increase the flow path resistance of the air flow path on the outlet side of the adsorption tank 12,
The pressure (swing pressure) in the adsorption tank 12 is set to a pressure suitable for nitrogen adsorption (for example, 0.5 kgf / cm 2 G) (see FIGS. 6 and 7). As described above, under the pressure condition suitable for the adsorption of nitrogen, the air is circulated through the path of the first port P1 → the adsorption tank 12 → the second port P2, so that the adsorption agent 13 is accommodated in the adsorption tank 12. Air is evenly distributed throughout the region to efficiently adsorb nitrogen in the air and efficiently generate oxygen-enriched air.

The operation in the oxygen enrichment mode as described above is executed for 20 seconds by the relay timer RLT (step 103). This relay timer RLT
After the oxygen enrichment mode ends, relay switch SW2
SW3 is kept on for 20 seconds, for example, and the solenoid valve E
Power is supplied to V3, EV4, EV9, and EV10, these are maintained in the open state, and the operation in the deaeration mode is executed for, for example, 20 seconds (step 107).

In this deaeration mode, the surge tank 22
The oxygen-enriched air stored in the solenoid valve EV4 → second port P2 → adsorption tank 12 → first port P1 → solenoid valve EV3 → solenoid valve E as shown by a dotted arrow in FIG.
It is discharged outside the room through the route of V9 → compressor 11 → electromagnetic valve EV10. At this time, the oxygen-enriched air is absorbed in the adsorption tank 12
In the process of passing through the adsorbent 13, the nitrogen molecules and carbon dioxide molecules adsorbed by the adsorbent 13 are removed to restore the adsorption ability of the adsorbent 13. The pressure in the adsorption tank 12 in the degassing mode is, for example, -0.8 kgf / cm.
It is 2 G.

After completion of this degassing mode, step 101
If the oxygen concentration is 20.0% or less, the process proceeds to step 102 again, and the operation in the oxygen enrichment mode is repeated. As a result, if the oxygen concentration exceeds 20.0%, the determination in step 101 becomes "NO", and step 104
Then, the second relay coil RL2 is energized, the second relay switch RL2S is turned on, and the operation in the carbon dioxide removal mode is started.

In the carbon dioxide removal mode, as shown in FIG. 3, the solenoid valves EV1, EV2, EV6, EV7,
The EV 8 is opened, and the indoor air is supplied to the indoor air, as shown by the one-dot chain line arrow in FIG. -> 1st port P1-> bypass outflow path 19 (solenoid valve EV8)-> low pressure circuit 16 (solenoid valve EV6)-> It circulates by the path | route in a room, and reduces the carbon dioxide concentration in room air. At this time, the air is circulated in the path of the third port P3 → the adsorption tank 12 → the first port P1 so that the air circulation range in the accommodating region of the adsorbent 13 in the adsorption tank 12 is indicated by dotted diagonal lines in FIG. By narrowing to the range shown, the pressure loss in the adsorption tank 12 is reduced, and the pressure (swing pressure) in the adsorption tank 12 is reduced. Furthermore,
By flowing the air flowing out from the adsorption tank 12 through the low pressure circuit 16 (electromagnetic valve EV6), the flow path resistance of the air circulation path on the outlet side of the adsorption tank 12 is made small, and the swing pressure is suitable for adsorption of carbon dioxide. Pressure (eg 0.08kg
f / cm2 G) (see FIGS. 6 and 7). As a result, under a pressure condition suitable for adsorption of carbon dioxide, the flow rate of air is increased, carbon dioxide in the air is efficiently adsorbed, and the carbon dioxide concentration in the air is efficiently reduced. In this carbon dioxide removal mode, as shown in FIG. 7, the oxygen concentration in the supply air is reduced from 26.2% to 25%, the pressure loss in the adsorption tank 12 is decreased, and the flow path resistance of the air outflow path is increased. Due to the decrease, the air inflow rate increases from 7.2 liters / min to 14.3 liters / min. As a result, the amount of carbon dioxide removed increases from 0.0126 g / g to 0.0251 g / g by about two times. Such a carbon dioxide removal mode operation is terminated after, for example, 20 seconds (step 105), the process proceeds to step 106, and the deaeration mode operation is executed for 20 seconds (step 107).
Returning to step 101, the above processing is repeated thereafter.

In summary of the above processing contents, while the oxygen concentration exceeds 20.0%, the operation in the carbon dioxide removal mode and the deaeration mode are alternately repeated at intervals of, for example, 20 seconds so that the oxygen concentration is 20%. When it becomes 0.0% or less, the operation of the oxygen enrichment mode is executed to operate so that the oxygen concentration is higher than 20.0%. As a result, the indoor air environment is maintained within the range of the region I or the region II having a high fatigue reduction rate shown in FIG. 8, and the comfort of the indoor living space is maintained well.

In the first embodiment described above, the bypass outflow passage 19 through which air flows in the carbon dioxide removal mode is connected to the front stage of the surge tank 22 so that a part of the air remains in the surge tank 22 even in the carbon dioxide removal mode. However, as in the second embodiment of the present invention shown in FIG. 9, the outlet of the bypass outlet 31 connected to the first port P1 side of the adsorption tank 12 is connected to the high voltage circuit 15. Of the solenoid valve E in the bypass outflow passage 31.
A configuration in which V8 is provided may be used.

In this case, the bypass outflow passage 31 constitutes the flow mode switching means 32 together with the bypass inflow passage 18 as in the first embodiment, and removes carbon dioxide from the oxygen enrichment mode in the air flow in the adsorption tank 12. It serves to switch to mode. Further, the bypass outflow passage 31 also functions as a "low pressure circuit", and the pressure (swing pressure) in the adsorption tank 12 during the carbon dioxide removal mode is a pressure suitable for adsorbing carbon dioxide (for example, 0.08 kgf / cm2 G). ). Therefore, in the second embodiment, the flow path resistance switching means 33 is composed of the bypass outflow passage 31 and the high voltage circuit 15. In the second embodiment, as a result of changing the connection of the bypass outflow passage 31 from the first embodiment, the connection between the second port P2 of the adsorption tank 12 and the surge tank 22 is provided in the first embodiment. Solenoid valve E used
V4 becomes unnecessary. The configuration other than this is the same as that of the first embodiment described above.

In both the first and second embodiments described above, the flow mode switching means 21 and 32 are provided, and in the carbon dioxide removing mode, air is supplied to the third port P3 → adsorption tank 12 → first port P1. Since the air is made to flow so as to narrow the air circulation range in the storage area of the adsorbent 13 in the adsorption tank 12 by circulating the air through the path of, the pressure loss in the adsorption tank 12 in the carbon dioxide removal mode is reduced. It is possible to increase the swing pressure drop range,
The air flow rate can be increased to increase carbon dioxide removal. Moreover, when viewed from the whole adsorbent 13, the part for adsorbing carbon dioxide (the part shown by the dotted diagonal line in FIG. 2)
Therefore, even if desorption of carbon dioxide with strong adsorption power becomes insufficient, it is possible to secure the nitrogen adsorption capacity in the oxygen enrichment mode by the part that does not adsorb carbon dioxide, It is possible to suppress a decrease in oxygen enrichment capacity to a small extent, and it is possible to perform both oxygen enrichment and carbon dioxide removal extremely efficiently by using one adsorption tank 12.

However, the present invention is not limited to both the first and second embodiments. For example, the distribution mode switching means 21 and 32 may be omitted as in the third embodiment shown in FIG. good. In the third embodiment, even in the carbon dioxide removal mode, air is circulated through the route of the first port P1 → adsorption tank 12 → second port P2, as in the oxygen enrichment mode. By flowing the air flowing out of the tank 12 through the low-pressure circuit 16 (electromagnetic valve EV6) of the flow path resistance switching means 17, the flow path resistance of the air flow path on the outlet side of the adsorption tank 12 is reduced, and the swing pressure is lowered. Can be made. Thereby, the air flow rate can be increased to increase the carbon dioxide removal amount, and both the oxygen enrichment and the carbon dioxide removal can be efficiently performed by using one adsorption tank 12. Incidentally, in the third embodiment, as a result of omitting the distribution mode switching means 21, 32, the solenoid valves EV3, E provided in the first embodiment.
V4 is also unnecessary.

Further, the present invention may have a configuration in which the flow path resistance switching means 17 and 33 are omitted from the configuration of the first or second embodiment. Even in this case, the distribution mode switching means 2
By 1, 32, the pressure loss in the adsorption tank 12 can be reduced to reduce the swing pressure in the carbon dioxide removal mode, and the air flow rate can be increased to increase the carbon dioxide removal amount.

In the first embodiment described above, the carbon dioxide sensor is omitted from the design requirement of reducing the number of sensors, and when the oxygen concentration in the air exceeds 20.0%, the carbon dioxide removal mode is set. Although the operation in the degassing mode is alternately repeated at intervals of, for example, 20 seconds, a carbon dioxide sensor (carbon dioxide detecting means) is provided and the carbon dioxide concentration in the room air is set to a set value (for example, 0.5%). When exceeding the limit, the operation in the carbon dioxide removal mode may be performed.

An embodiment embodying this is shown in FIGS.
4 is a fourth embodiment of the present invention shown in FIG. In the fourth embodiment, the carbon dioxide sensor 4 is used as the carbon dioxide concentration detecting means.
1, the output signal of the carbon dioxide sensor 41 is input to the control circuit 42 (control means). The control circuit 42 is mainly composed of, for example, a microcomputer, and executes the control program shown in FIG. 12 so that when the carbon dioxide concentration in the room air exceeds a set value (for example, 0.5%), The flow path resistance switching means 17 (or 33) or the flow mode switching means 21 (or 32) is controlled to switch to the carbon dioxide removal mode for operation. Here, either one of the flow path resistance switching means 17 (or 33) and the distribution mode switching means 21 (or 32) may be provided, and the configuration thereof may be one of the embodiments described above. Just do it.

As described above, even if the oxygen concentration is high, if the carbon dioxide concentration is high, the fatigue reduction rate (comfort) will be significantly reduced. Therefore, in order to maintain comfort, it is also necessary to lower the carbon dioxide concentration in addition to oxygen enrichment. A closer examination of this relationship confirmed that the better the air quality (carbon dioxide concentration and oxygen concentration), the more the respiratory volume of the human body can be reduced.
This respiration rate is an index showing the metabolic rate of the human body, and it is considered that the magnitude of the metabolic rate affects not only physical fatigue but also mental fatigue. Therefore, suppressing an increase in metabolic rate (in this case, an increase in respiratory rate) is considered to be better air purification.

According to the results of experiments conducted by the present inventor, as shown in FIG. 13, it was confirmed that oxygen enrichment can reduce the respiration rate, but as the carbon dioxide concentration increases, the respiration rate increases, It was confirmed that when the carbon dioxide concentration is high, the respiratory volume cannot be reduced to the level in the clean environment even if the oxygen is enriched. For example, as shown in FIG. 13A, in a clean environment (carbon dioxide concentration: about 0.04
%, Oxygen concentration; about 21%), the respiratory volume is about 9.
Although it is 5 liters / minute, as shown in FIG.
Carbon dioxide concentration rises to about 0.7%, oxygen concentration about 2
Reducing to 0% increases breathing volume to about 13 liters / minute. In such a state, even if the oxygen concentration is increased to raise the oxygen concentration to about 30%, as shown in FIG. 13 (c), the respiration rate can be reduced to only about 12 liters / minute, and the clean environment is reduced. It cannot be reduced to the hourly level. In such a case, as shown in FIG. 14, it was also confirmed that lowering the carbon dioxide concentration was more effective in reducing the respiratory volume than oxygen enrichment.

Focusing on this relationship, the structure for realizing a more comfortable air quality is the above-mentioned fourth embodiment. In the fourth embodiment, the subroutine shown in FIGS. 12A and 12B is repeatedly executed during the execution of the main control program (not shown), and the carbon dioxide concentration is set to a set value (for example, 0.5%). It can be kept below.

In the subroutine (No. 1) shown in FIG. 12A, first, at step 111, it is judged if the operation is in the oxygen enrichment mode. If "NO", the process returns to the main control program. After that, if the oxygen enrichment mode operation is started, the determination at step 111 is “YE
S ”, the routine proceeds to step 112, where it is judged whether or not the carbon dioxide concentration detected by the carbon dioxide sensor 41 exceeds a set value (for example, 0.5%). If the carbon dioxide concentration is less than or equal to the set value, it is sufficient to continue the oxygen enrichment mode operation, so the process returns to the main control program without performing step 113.

Thereafter, if the carbon dioxide concentration exceeds the set value, the determination at step 112 described above is "Y".
ES ”, the process proceeds to step 113, and the operation mode is switched to the carbon dioxide removal mode. Thereby, the carbon dioxide concentration can be suppressed below the set value. For this reason, it is possible to effectively reduce the breathing volume and further improve the comfort as compared with the case where the oxygen enrichment is continued while the carbon dioxide concentration is high, and the subsequent oxygen enrichment is also effective. Can be done.

On the other hand, the return timing from the carbon dioxide removal mode to the oxygen enrichment mode is controlled by the subroutine (No. 2) shown in FIG. 12 (b). In this subroutine (No. 2), first, in step 121, it is determined whether or not the carbon dioxide removal mode operation is in progress. If "NO", the process returns to the main control program. After that, if the operation mode is switched to the carbon dioxide removal mode, the determination in step 121 is “YES” at that point, the process proceeds to step 122, and the carbon dioxide concentration detected by the carbon dioxide sensor 41 is a return value (for example, 0). .2%) or less. If the carbon dioxide concentration is higher than the return value, it is necessary to continue the operation in the carbon dioxide removal mode to reduce the carbon dioxide concentration. Therefore, the process of step 123 is not performed and the main control program is executed. Return.

After that, when the carbon dioxide concentration becomes equal to or lower than the return value, the determination at step 122 described above becomes "YES" at that time, and the routine proceeds to step 123, where the operation mode is switched to the oxygen enrichment mode. As a result, oxygen enrichment can be effectively performed while the carbon dioxide concentration is reduced.

Further, in the fourth embodiment, the "economy mode" for adjusting the breathing amount to the level in the clean environment and the "fatigue recovery mode" for reducing the breathing amount below the level in the clean environment are switched. Mode changeover switch 43
(See FIG. 11). The basic concept of this mode switching is shown in FIG. It is said that the limit value of the oxygen concentration at which a person feels comfortable or does not cause poisoning due to the addition of high concentration oxygen is about 40%. Therefore, in the fatigue recovery mode, while the oxygen sensor 44 monitors the oxygen concentration in the indoor air, the operation in the oxygen enrichment mode is controlled so that the oxygen concentration is enriched within the range of 40% or less. However, even in this fatigue recovery mode, if the carbon dioxide concentration exceeds the set value, at that point, the operation mode is switched to the carbon dioxide removal mode, the carbon dioxide concentration is kept below the set value, and the oxygen enrichment after that is reduced. Enhance the effect.

Further, if the carbon dioxide concentration is low, the degree of oxygen enrichment may be small, so in the economy mode, the oxygen enrichment amount is reduced as the carbon dioxide concentration decreases. In this case, when the oxygen concentration exceeds the upper limit value of the economy mode, the operation of the oxygen enrichment mode is stopped, and then when the oxygen concentration falls below the lower limit value of the economy mode, the operation of the oxygen enrichment mode is stopped. The energy saving is achieved by intermittently performing the operation in the oxygen enrichment mode such as restarting. However, even in this economy mode, if the carbon dioxide concentration exceeds the set value, at that point, the operation mode is switched to the carbon dioxide removal mode, the carbon dioxide concentration is kept below the set value, and the effect of subsequent oxygen enrichment is reduced. Increase.

Since individual individuals have different sensitivities to carbon dioxide and oxygen, the range of the economy mode and the set value at the time of switching to the carbon dioxide removal mode should be varied,
You may make it possible to adjust these according to a user's preference. Further, in the fourth embodiment, the carbon dioxide concentration is returned to the oxygen enrichment mode when the carbon dioxide concentration becomes equal to or lower than the reset value during the carbon dioxide removal mode operation. However, the operation of the carbon dioxide removal mode is controlled by a timer. Alternatively, the operation in the carbon dioxide removal mode may be performed for a certain period of time, and then the operation may be returned to the oxygen enrichment mode.

Further, in the above-described first to third embodiments, the switching of the operation of the oxygen enrichment mode, the carbon dioxide removal mode, and the degassing mode is not manually switched but manually switched by a manual switch. It goes without saying that it is okay.

Besides, the present invention is not limited to the above-mentioned respective embodiments, and for example, the oxygen concentration set value at the start of the operation of the oxygen enrichment mode is changed from 20%, or the mode is switched to the carbon dioxide removal mode. The set value of carbon dioxide concentration at that time is changed from 0.5%, the set value of carbon dioxide concentration (return value) at the time of returning to the oxygen enrichment mode is changed from 0.2%, and the air feeding means is compressed by the compressor. Needless to say, various modifications can be made without departing from the spirit of the present invention, such as changing from 11 to a blower, or changing the swing pressure appropriately according to the size and structure of the adsorption tank 12.

[0052]

As is apparent from the above description, according to the present invention, the flow path resistance switching means for switching the flow path resistance of the air flow path on the outlet side of the adsorption tank, or the air flow in the adsorption tank. Since the distribution mode switching means for switching between the two is used, by the switching operation, it is possible to efficiently perform both oxygen enrichment (removal of nitrogen) and removal of carbon dioxide by using one adsorption tank. Both the concentration and the carbon dioxide concentration can be appropriately controlled, and an extremely comfortable air environment can be realized (effects of claims 1 and 3).

Further, when the carbon dioxide concentration exceeds the set value, the operation is automatically switched to the carbon dioxide removal mode, so that the carbon dioxide concentration can be suppressed below the set value. Respiratory volume can be effectively reduced compared to when oxygen enrichment is continued while the carbon dioxide concentration is high, and comfort can be further improved, and subsequent oxygen enrichment can be more effectively performed. (Effects of claims 2 and 4).

[Brief description of drawings]

FIG. 1 is a system configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a front view showing a partial cutaway of the adsorption tank.

FIG. 3 is a diagram showing a relationship between each mode and ON / OFF of each solenoid valve.

[Fig. 4] Electric circuit diagram of control system

FIG. 5 is a flowchart showing the operation contents of the oxygen-enriched air generator.

FIG. 6 is a diagram showing a relationship between a swing pressure, a carbon dioxide adsorption amount, an oxygen enrichment amount, an air flow rate, and a carbon dioxide / nitrogen saturated adsorption amount.

FIG. 7 is a diagram showing the relationship between swing pressure, oxygen concentration (a), and carbon dioxide removal amount (b).

FIG. 8 is a diagram showing a relationship between an air environment and a fatigue reduction rate.

FIG. 9 is a system configuration diagram showing a second embodiment of the present invention.

FIG. 10 is a system configuration diagram showing a third embodiment of the present invention.

FIG. 11 is a block diagram showing a fourth embodiment of the present invention.

FIG. 12 is a flowchart showing the control flow of two subroutines.

FIG. 13 is a diagram showing the relationship between respiratory volume, carbon dioxide concentration, and oxygen concentration.

FIG. 14 is a diagram for explaining the relationship between the oxygen enrichment amount and the carbon dioxide concentration required to return the respiratory volume to the level in the clean environment.

FIG. 15 is a diagram illustrating the concepts of economy mode and fatigue recovery mode.

[Explanation of symbols]

11 ... Compressor (air supply means), 12 ... Adsorption tank,
13 ... Adsorbent, 14 ... Orifice, 15 ... High-voltage circuit, 1
6 ... Low-voltage circuit, 17 ... Flow path resistance switching means, 18 ... Bypass inflow path, 19 ... Bypass outflow path, 21 ... Flow mode switching means, 22 ... Surge tank, 31 ... Bypass outflow path,
32 ... Distribution mode switching means, 33 ... Flow path resistance switching means,
41 ... Carbon dioxide sensor (carbon dioxide concentration detecting means),
42 ... Control circuit (control means), 43 ... Mode change switch, 44 ... Oxygen sensor, EV1-EV10 ... Solenoid valve, P
1 ... 1st port, P2 ... 2nd port, P3 ... 3rd port.

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[Procedure amendment]

[Submission date] January 12, 1994

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] Figure 8

[Correction method] Change

[Correction content]

[Figure 8]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor ▲ Child ▼ Tama Satoru 1-1, Showa-cho, Kariya city, Aichi Prefecture Nihondenso Co., Ltd.

Claims (4)

[Claims] 1. An oxygen-enriched air production system, wherein an adsorption tank containing an adsorbent for adsorbing nitrogen and carbon dioxide in air is provided, and air is sent into the adsorption tank by an air supply means to produce oxygen-enriched air. In the device, by switching the flow path resistance of the air circulation path on the outlet side of the adsorption tank, the pressure inside the adsorption tank is set to a pressure suitable for adsorption of nitrogen, and is suitable for adsorption of carbon dioxide and an oxygen enrichment mode. An oxygen-enriched air generation device, characterized in that it is provided with a flow path resistance switching means for switching between a carbon dioxide removal mode in which the pressure is set to a predetermined pressure and a carbon dioxide removal mode. 2. A carbon dioxide concentration detecting means for detecting a carbon dioxide concentration in indoor air, and when the detected carbon dioxide concentration exceeds a set value, the flow path resistance switching means is switched to a carbon dioxide removing mode for operation. 2. The oxygen-enriched air generator according to claim 1, further comprising: 3. An oxygen-enriched air production system, wherein an adsorption tank containing an adsorbent for adsorbing nitrogen and carbon dioxide in the air is provided, and air is sent to the adsorption tank by air supply means to produce oxygen-enriched air. In the apparatus, an oxygen enrichment mode in which the air flow in the adsorption tank is spread over the entire adsorbent storage area, and a pressure loss in the adsorption tank is caused by flowing air so as to narrow the air flow range in the adsorbent storage area. An oxygen-enriched air generation device, characterized in that a distribution mode switching means is provided for switching between a carbon dioxide removal mode for lowering and a carbon dioxide removal mode. 4. A carbon dioxide concentration detecting means for detecting a carbon dioxide concentration in indoor air, and when the detected carbon dioxide concentration exceeds a set value, the flow mode switching means is switched to a carbon dioxide removing mode to operate. The oxygen-enriched air generator according to claim 3, further comprising a control means.