JPH1085545A - Dry air supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the dew point of dry compressed air generated by a membrane-type air dryer so that the dew point is appropriate for air pressure equipment. SOLUTION: An inflow valve 25 is installed on the inflow side of a membrane-type air dryer 23 and an outflow valve 26 is installed on the outflow side of the membrane-type air dryer 23. Further, an air pressure in an air tank 22 is detected by an air pressure detector 31, and an air compressor 21, the inflow valve 25 and the outflow valve 26 are controlled using a controller 32, based on the detection results of the air pressure detector 31 to set the inflow pressure of the membrane-type air dryer 23 to an appropriate dew point setting pressure level. Consequently, it is possible to supply a dry compressed air at an appropriate dew point to air pressure equipment 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry air supply device for supplying dry compressed air to, for example, a pneumatic device, and more particularly to a dry air supply device using a film air dryer.

[0002]

2. Description of the Related Art As shown in FIG. 6, a dry air supply device according to the prior art includes an air compressor 1 for supplying compressed air,
An inflow side is connected to the air compressor 1, an air tank 2 for storing compressed air supplied from the air compressor 1, and a compressed air flowing out of the air tank 2 connected to an outflow side of the air tank 2. Membrane air dryer 3 for drying and producing dry compressed air
It is composed of

[0003] The air compressor 1 has a compressor body 1A.
And an electric motor 1B for driving the compressor body 1A. A pneumatic device 4 is connected downstream of the membrane air dryer 3. The pneumatic device 4 is, for example, a gas separation device, an air cylinder, an air motor, or the like. Furthermore, a throttle 5 for adjusting the amount of compressed air supplied from the film air dryer 3 to the pneumatic device 4 is provided in the middle of a pipe connecting the film air dryer 3 and the pneumatic device 4. Is provided.

In the dry air supply apparatus according to the prior art configured as described above, when compressed air is supplied to the pneumatic device 4, the compressor body 1A is driven by driving the electric motor 1B, and the compressor body 1A is driven. To supply compressed air to the air tank 2. Then, the compressed air stored in the air tank 2 is supplied to the membrane air dryer 3, and the compressed air is dried by the membrane air dryer 3. To supply.

Here, a detailed configuration of the film air dryer 3 will be described with reference to FIG. The membrane air dryer 3
A dehumidifying passage 8 disposed between the inflow port 6 and the outflow port 7 and formed hollow using a dehumidifying film made of a fiber material (hollow fiber) such as polyimide, and surrounds the dehumidifying passage 8 from outside. A discharge passage 9 formed to have a tubular shape and discharging steam separated from the compressed air flowing in the dehumidifying passage 8, an air recirculation passage 10 for returning a part of the air flowing in the dehumidifying passage 8 to the discharge passage 9, And a discharge pipe 11 for discharging air flowing through the discharge passage 9 into the atmosphere.

When the compressed air from the air tank 2 flows in the dehumidifying passage 8 from the inflow port 6 to the outflow port 7 in the direction indicated by the arrow in FIG. 7, the water vapor contained in the compressed air is dissipated from the air. Through the dehumidifying passage 8 with a high permeation speed.
In this way, the membrane air dryer 3 separates the water vapor in the compressed air, and draws out the dry compressed air having a low dew point to the outlet 7 side.

The membrane air dryer 3 recirculates a part of the dried compressed air led out to the outlet 7 through an air recirculation passage 10 into a discharge passage 9. Water vapor is removed from the outer peripheral surface of the dehumidifying passage 8 and the discharge pipe 1
It is configured to discharge (purge) from 1 to the atmosphere. Thus, the dehumidifying film of the film air dryer 3 is regenerated.

[0008]

In the above-mentioned prior art, the compressed air flowing out of the air tank 2 is directly supplied to the membrane air dryer 3. For this reason, when the air pressure in the air tank 2 is reduced, for example, when the supply of compressed air from the air compressor 1 to the air tank 2 is insufficient, the air pressure at the inlet 6 of the membrane air dryer 3, that is, The inflow pressure of the air dryer 3 decreases.

Further, the membrane air dryer 3 includes a dehumidifying passage 8.
A part of the compressed air led to the outlet 7 through the air is returned to the discharge passage 9 through the air return passage 10 so that the air flow removes water vapor from the outer peripheral surface of the dehumidifying passage 8. It is configured. For this reason, the membrane air dryer 3
When the inflow pressure of the compressed air decreases, the dew point of the dry compressed air generated by the membrane air dryer 3 rises, and there is a problem that the dry compressed air having an appropriate dew point cannot be supplied to the pneumatic device 4.

[0010] The membrane air dryer 3 has a predetermined inflow pressure allowable range in which the membrane air dryer 3 can perform the function of drying compressed air. The allowable range of the inflow pressure is determined by the physical properties of the dehumidifying film constituting the membrane air dryer 3 and is defined as a rating for the membrane air dryer 3. For this reason,
The air pressure in the air tank 2 is greatly reduced, and the film air dryer 3
If the inflow pressure of the air becomes lower than the inflow pressure allowable range, the compressed air cannot be dried by the membrane air dryer 3 and the compressed air having a high dew point containing a large amount of water vapor is supplied to the pneumatic device 4. There is a problem of being supplied.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and it has been proposed that the dew point of the dry compressed air generated by the membrane air dryer be adjusted to an appropriate dew point for pneumatic equipment. It is an object of the present invention to provide a dry air supply device capable of setting an inflow pressure of an air dryer.

[0012]

According to a first aspect of the present invention, there is provided an air compressor for supplying compressed air and an air tank for storing compressed air supplied from the air compressor. A membrane air dryer for drying compressed air flowing out of the air tank, an on-off valve provided between an inflow side of the membrane air dryer and the air tank, and an inflow valve into the membrane air dryer. An air pressure detector for detecting an air pressure to be detected, and determining whether or not the air pressure detected by the air pressure detector is equal to or higher than an appropriate dew point set pressure. Valve control means for opening the on-off valve when the pressure exceeds the set pressure.

According to the above configuration, when dry compressed air is supplied to a pneumatic device or the like, first, with the on-off valve closed,
The air compressor is driven to supply compressed air to the air tank. At this time, the air pressure detector detects the air pressure flowing into the membrane air dryer, and the valve control unit receives the detection result of the air pressure detector and determines whether or not this air pressure is equal to or higher than the appropriate dew point set pressure. Here, the appropriate dew point set pressure is a pressure value determined so that the dew point of the dry compressed air flowing out from the outflow side of the film air dryer is set to an appropriate dew point for a pneumatic device or the like.

Subsequently, the valve control means determines whether or not the air pressure flowing into the film air dryer is equal to or higher than the appropriate dew point set pressure. If the air pressure is lower than the appropriate dew point set pressure, the valve control means closes the on-off valve. Maintain the valved state. Thereby, the compressed air supplied from the air compressor is stored in the air tank, so that the air pressure in the air tank increases, and the air pressure flowing into the membrane air dryer increases.

On the other hand, the valve control means determines whether or not the air pressure flowing into the membrane air dryer is equal to or higher than the appropriate dew point set pressure. Open the valve. Thereby, the compressed air in the air tank is supplied to the membrane air dryer, and the membrane air dryer generates dry compressed air. Then, the dry compressed air is supplied to a pneumatic device or the like.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a dry air supply device according to the present invention will be described below in detail with reference to FIGS.

In FIG. 1, reference numeral 21 denotes an air compressor for supplying compressed air. The air compressor 21 has a compressor body 21A and a compressor body 21A, like the air compressor 1 described in the prior art. And an electric motor 21B for driving the motor 21A. Further, the electric motor 21B is electrically connected to a controller 32 described later. As a result, the driving and stopping of the air compressor 21 is controlled by the control signal output from the controller 32.

Reference numeral 22 denotes an air tank for storing compressed air supplied from the air compressor 21. The inflow side of the air tank 22 is connected to the air compressor 21 via an air pipe.

Reference numeral 23 denotes an air pipe 24 on the outflow side of the air tank 22.
Shows a membrane air dryer connected through the, the membrane air dryer 23 is to remove the water vapor contained in the compressed air supplied from the air tank 22, to produce dry compressed air, The membrane air dryer 23 is configured similarly to the membrane air dryer 3 according to the prior art shown in FIG. In addition,
The film air dryer 23 may be any device that removes water vapor contained in compressed air using a dehumidifying film, and is not limited to the configuration shown in FIG.

Reference numeral 25 denotes an inflow valve as an on-off valve provided in the middle of the air pipe 24. The inflow valve 25 is provided in the air tank 2
An electromagnetic valve that communicates with and shuts off the air dryer 2 and the membrane air dryer 23. The inflow valve 25 is electrically connected to the controller 32. Thus, the inflow valve 25 is normally closed to keep the air pipe 24 in a shut-off state. However, when the controller 32 outputs a valve opening signal, the valve is opened,
The air pipe 24 is brought into a communicating state.

Reference numeral 26 denotes an outflow valve provided in the middle of an air pipe 27 connecting the membrane air dryer 23 and the pneumatic device 4, and the outflow valve 26 is provided with the membrane air dryer 23 and the pneumatic device 4. 4
A solenoid valve that communicates and shuts off between The outflow valve 26 is electrically connected to a controller 32. Thereby, the outflow valve 26 is normally closed and the air pipe 2 is closed.
7 is shut off, but when a valve opening signal is output from the controller 32, the valve is opened and the air pipe 27 is brought into a communicating state.

Reference numeral 28 denotes a throttle for adjusting the flow rate of dry compressed air supplied to the pneumatic device 4. The throttle 28 is located between the outflow valve 26 and the pneumatic device 4, and is provided in the air pipe 27. Have been.

Reference numeral 29 denotes a relief pipe having one end connected to the air tank 22 and the other end open to the atmosphere. Reference numeral 30 denotes a relief valve connected in the middle of the relief pipe 29. , And is electrically connected to the controller 32. Although the relief valve 30 is normally closed, the controller 32
The valve is opened when a valve opening signal is output from the controller, and excess compressed air in the air tank 22 is released to the atmosphere.

Reference numeral 31 denotes an air pressure detector provided in the air tank 22. The air pressure detector 31 is constituted by a pressure gauge (pressure converter) for converting air pressure into an electric quantity.
2 detects the air pressure in the membrane air dryer 2
3 is to detect the air pressure flowing into 3. The air pressure detector 31 is connected to the controller 32 and outputs a detection signal corresponding to the air pressure in the air tank 22 to the controller 32.

Reference numeral 32 denotes a controller as valve control means. The controller 32 is, for example, a microcomputer including a CPU, a storage circuit, an input / output circuit, a timer, and the like. An air pressure detector 31 is connected to an input terminal of the controller 32.
Output terminals of the electric compressor 21B of the air compressor 21,
The inflow valve 25, the outflow valve 26, and the relief valve 30 are connected.

The storage circuit 32 of the controller 32
A stores a program for performing a dry air supply process described later, a lower limit pressure P1, an appropriate dew point set pressure P2, a highest set pressure P3, and an upper limit pressure P4.

The controller 32 receives a detection signal output from the air pressure detector 31 and outputs a control signal to the air compressor 21 based on the detection signal, as described later. In addition to controlling driving and stopping, a valve opening signal is output to the inflow valve 25, the outflow valve 26 or the relief valve 30, and the opening and closing of the inflow valve 25, the outflow valve 26 or the relief valve 30 is controlled.

Here, the lower limit pressure P1 and the appropriate dew point set pressure P
2, the maximum set pressure P3 and the upper limit pressure P4 will be described with reference to the characteristic diagram shown in FIG. The horizontal axis of the characteristic diagram shown in FIG. 2 indicates the inflow pressure of the membrane air dryer 23, and the vertical axis indicates the dew point of the dry compressed air generated by the membrane air dryer 23.

The "lower limit pressure P1" is a lower limit value of an allowable inflow pressure range in which the film air dryer 23 can perform a function of drying compressed air. The “upper limit pressure P4” is the upper limit of the allowable range of the inflow pressure. This allowable range of inflow pressure is
It is determined by the physical properties and the like of the dehumidifying film constituting the film air dryer 23, and is determined as a rating for the film air dryer 23. Therefore, in order to operate the membrane air dryer 23 normally and to generate dry compressed air normally, the inflow pressure of the membrane air dryer 23 is set to the lower limit pressure P1.
To the upper limit pressure P4.

The “appropriate dew point setting pressure P 2” is a pressure value determined so that the dew point of the dry compressed air flowing out from the film air dryer 23 is set to an appropriate dew point for the pneumatic device 4. When the inflow pressure of the membrane air dryer 23 is equal to or higher than the appropriate dew point set pressure P2 and smaller than the upper limit pressure P4, the dew point of the dry compressed air generated by the membrane air dryer 23 is equal to or less than the "appropriate dew point D", The dew point of the dry compressed air is suitable for the pneumatic device 4.

Further, the "maximum set pressure P3" is a pressure value set in order to prevent the inflow pressure of the membrane air dryer 23 from rising and exceeding the upper limit pressure P4.

In the dry air supply process described later,
The inflow pressure of the membrane air dryer 23 is adjusted to an appropriate dew point set pressure P2
By setting the pressure within the range of the maximum set pressure P3, dry compressed air having a dew point appropriate for the pneumatic device 4 is supplied.

When a super dryer SU3000 manufactured by CKD is used as the membrane air dryer 23, the lower limit pressure P1 is 4.1 kgf / c.
m ² and upper limit pressure P4 = 10.2 kgf / cm ² . Further, the appropriate dew point set pressure P2 is also determined by the pneumatic device 4, for example, P2 = 7.0 kgf / cm ² . Further, the maximum set pressure P3 is, for example, 0.5 kg higher than the upper limit pressure P4.
f / cm ² smaller, P3 = 9.7 kgf /
cm ² .

The dry air supply device according to the embodiment of the present invention has the above-described configuration. Next, the operation of the dry air supply device will be described.

When the dry air supply device is driven to supply the dry compressed air from the dry air supply device to the pneumatic device 4, the dry air supply process shown in FIGS. 3 to 5 is started.

First, steps 1 to 11 in FIG.
Then, before starting the supply of the dry compressed air to the pneumatic device 4, the dry air supply device is initialized (step 1),
The moisture adhering to the dehumidifying film of the film air dryer 23 is removed, and the dehumidifying film of the film air dryer 23 is regenerated (steps 2 to 11). Hereinafter, such processing will be described in detail.

In step 1, the inflow valve 25 and the outflow valve 26
Then, the relief valve 30 is closed, and the dry air supply device is initialized.

In step 2, the air pressure P in the air tank 22 is determined based on the detection signal output from the air pressure detector 31.
c is detected, and it is determined whether the air pressure Pc is equal to or lower than the maximum set pressure P3. When the air pressure Pc is equal to or lower than the maximum set pressure P3, it is determined to be "YES", and the process proceeds to step 10. On the other hand, if the air pressure Pc is not equal to or less than the maximum set pressure P3, the determination is "NO" and the routine proceeds to step 3.

In step 3, the air pressure P in the air tank 22
It is determined whether or not c is equal to or higher than the upper limit pressure P4. When the air pressure Pc is equal to or higher than the upper limit pressure P4, it is determined to be "YES",
Move to step 4.

In step 4, the relief valve 30 is opened. As a result, excessive compressed air in the air tank 22 flows through the relief pipe 29 and is released into the atmosphere, so that the air pressure Pc in the air tank 22 decreases.

In step 5, the air pressure P in the air tank 22
It is determined whether or not c is equal to or higher than the maximum set pressure P3. When the air pressure Pc is equal to or higher than the maximum set pressure P3, "YES" is determined, and Step 5 is repeated. On the other hand, if the air pressure Pc is not equal to or higher than the maximum set pressure P3, "NO" is determined, and the routine proceeds to step 6, where the relief valve 30 is closed. Thereby, the compressed air in the air tank 22 is released to the atmosphere until the air pressure Pc in the air tank 22 becomes lower than the maximum set pressure P3.

On the other hand, after the execution of step 6 or because the air pressure Pc is not higher than the upper limit pressure P4 in step 3, "N
When it is determined to be "O", the process proceeds to step 7. In step 7, the inflow valve 25 is opened. As a result, compressed air is supplied from the air tank 22 to the film air dryer 23. At this time, since the outflow valve 26 provided on the outflow side of the membrane air dryer 23 is closed, the membrane air dryer 23 is closed.
Are used to regenerate the dehumidifying film of the film air dryer 23.

When the inflow valve 25 is opened in step 7, the air pressure Pc in the air tank 22 is at least equal to or less than the upper limit pressure P4. Since the inflow pressure of the membrane air dryer 23 is substantially equal to the air pressure Pc in the air tank 22, at the time when the inflow valve 25 is opened in step 7, the inflow pressure of the membrane air dryer 23 is at least the upper limit pressure P4. It is set as follows. Thus, the regeneration of the dehumidifying film of the film air dryer 23 is always normally performed by the processing of steps 8 and 9 described below.

In step 8, the air pressure P in the air tank 22
It is determined whether or not c is equal to or less than the appropriate dew point set pressure P2. If the air pressure Pc is not equal to or less than the appropriate dew point set pressure P2, the determination is "NO" and Step 7 is repeated. On the other hand, when the air pressure Pc is equal to or less than the appropriate dew point set pressure P2, “YE
S ”, the process proceeds to step 9, and the inflow valve 25 is closed. Thereby, the compressed air in the air tank 22 is supplied to the film air dryer 23 until the air pressure Pc in the air tank 22 reaches the appropriate dew point set pressure P2, and the dehumidifying film in the film air dryer 23 is regenerated. Will be

In step 10, the air compressor 21 is driven to start the dry operation of the dry air supply device. Thereby, compressed air is supplied to the air tank 22, and the air pressure Pc in the air tank 22 increases.

In step 11, it is determined whether the air pressure Pc in the air tank 22 is equal to or higher than the lower limit pressure P1. If the air pressure Pc is not equal to or higher than the lower limit pressure P1, it is determined to be "NO" and Step 11 is repeated. On the other hand, when the air pressure Pc is equal to or higher than the lower limit pressure P1, it is determined to be “YES”, and the process proceeds to step 12 in FIG. At the stage where step 12 has been completed, the air pressure Pc in the air tank 22 is set at least within the range of the lower limit pressure P1 to the highest set pressure P3.

Next, step 12 to step 2 in FIG.
At 0, before the supply of the dry compressed air to the pneumatic device 4 is started, the dry operation of the dry air supply device is performed for a predetermined time (dry operation time T), and the dehumidifying film of the film air dryer 23 is removed. Reproduce. In particular, during the dry operation of the dry air supply device, the air pressure Pc of the air tank 22 is adjusted to the appropriate dew point set pressure P2 to P2.
Maintained within the range of the maximum set pressure P3, the film air dryer 23
Is set so that the dew point of the dry compressed air generated by the above becomes appropriate for the pneumatic device 4. Hereinafter, such processing will be described in detail.

In step 12, after clearing the timer provided in the controller 32, the timer is started, and the dry air supply device starts idling. The dry operation of the dry air supply device is executed until the dry operation time T elapses from the present time.

Here, the "idle running time T" is set in advance and stored in the storage circuit 32A of the controller 32. Then, the idle operation time T includes a step 13 described later.
Through the processing in step 19, the air pressure P in the air tank 22
After increasing c to the maximum set pressure P3, the time until compressed air is supplied from the air tank 22 to the membrane air dryer 23 and the dehumidification membrane of the membrane dryer 23 can be properly regenerated. Is set. For example, the idle operation time T is about 4 seconds.

Subsequently, at step 13, it is determined whether or not the air pressure Pc of the air tank 22 is equal to or higher than the maximum set pressure P3 based on the detection signal output from the air pressure detector 31. If the air pressure Pc is not equal to or higher than the maximum set pressure P3, the determination is "NO", and the routine proceeds to step 14.

In step 14, the timer is set to the idle operation time T
Is determined. Then, when the timer has not elapsed the idle operation time T, the determination is “NO”, and the process returns to step S13. Steps 13 and 14 are repeated until the idle operation time T elapses. During this time, compressed air is supplied from the air compressor 21 to the air tank 22, and the air pressure Pc in the air tank 22 reaches the maximum set pressure P3.

When the air pressure Pc of the air tank 22 reaches the maximum set pressure P3, "YES" is determined in the step 13, and the process proceeds to the step 15. In this step 15,
The air compressor 21 is stopped, and the inflow valve 25 is opened. Thereby, the compressed air is transferred from the air tank 22 to the film air dryer 23.
Supplied to. At this time, since the outflow valve 26 provided on the outflow side of the membrane air dryer 23 is closed, all the compressed air supplied to the membrane air dryer 23 is Used to regenerate dehumidifying films.

In step 16, the air pressure P in the air tank 22
It is determined whether or not c is equal to or less than the appropriate dew point set pressure P2. When the air pressure Pc is not equal to or less than the appropriate dew point set pressure P2, the determination is "NO", and the routine proceeds to step 17.

In step 17, the timer is set to the idle operation time T.
Is determined. Then, when the timer has not elapsed the idle operation time T, the determination is “NO”, and the process returns to step 16. Thus, the air pressure P of the air tank 22
Steps 16 and 17 until c becomes equal to or lower than the appropriate dew point set pressure P2 or until the idling time T elapses.
repeat.

Then, while Steps 16 and 17 are repeated, the compressed air in the air tank 22 is supplied to the membrane air dryer 2.
3 and the regeneration of the dehumidifying film of the film air dryer 23 is continued. During this time, the air pressure Pc in the air tank 22 is:
Since it is within the range of the appropriate dew point set pressure P2 to the maximum set pressure P3, the inflow pressure of the film air dryer 23 also falls within the range of the appropriate dew point set pressure P2 to the maximum set pressure P3. As a result, air having a flow rate appropriate for drying the compressed air flows into the membrane air dryer 23, so that the dew point of the dry compressed air generated by the membrane air dryer 23 is appropriate for the pneumatic device 4. Dew point (appropriate dew point D or less).

If the air pressure Pc in the air tank 22 decreases during the steps 16 and 17 and the air pressure Pc becomes equal to or lower than the appropriate dew point set pressure P2, "YES" is determined in the step 16, and "YES" is determined in the step 16. The program then proceeds to step 18 where the inflow valve 25 is closed and the air compressor 21 is driven.

Subsequently, the process proceeds from step 18 to step 14, and in step 14, it is determined whether or not the timer has exceeded the idle operation time T. Then, the timer is set to the idle operation time T.
Is determined to be “YES”, and step 20 is performed.
And the timer is stopped at step 20. On the other hand, when the timer has not elapsed the idle operation time T, the determination is “NO”, and the process returns to step S13.

On the other hand, if the idle operation time T has elapsed during the repetition of steps 16 and 17, it is determined to be "YES" in step 17, and the process proceeds to step 19.
Then, in step 19, as in step 17, the inflow valve 25 is closed and the air compressor 21 is driven. Then, the process proceeds to step 20 to stop the timer. At the end of step 20, the air tank 2
2, the air pressure Pc is always set within the range of the appropriate dew point set pressure P2 to the maximum set pressure P3.

Next, steps 21 to 2 in FIG.
At 8, dry compressed air is actually supplied to the pneumatic device 4. In particular, while the dry compressed air is being supplied to the pneumatic device 4, the air pressure Pc of the air tank 22 is adjusted to the appropriate dew point set pressure P2 to P2.
Maintained within the range of the maximum set pressure P3, the film air dryer 23
Is maintained so that the dew point of the dry compressed air generated by the above becomes an appropriate dew point for the pneumatic device 4. Hereinafter, such processing will be described in detail.

In step 21, the inflow valve 25 and the outflow valve 2
The valve 6 is opened, and a passage from the air tank 22 to the pneumatic device 4 via the membrane air dryer 23 is communicated. As a result, the compressed air is supplied from the air tank 22 to the membrane air dryer 23, and the moisture is removed from the compressed air by the membrane air dryer 23, and the compressed air is supplied to the pneumatic device 4 as dry compressed air. .

In step 22, it is determined based on the detection signal output from the air pressure detector 31 whether the air pressure Pc in the air tank 22 is equal to or lower than the maximum set pressure P3. And
When the air pressure Pc is equal to or lower than the maximum set pressure P3, "YES"
And the process proceeds to step 26. On the other hand, the air pressure Pc
Is not less than the maximum set pressure P3, the determination is "NO", and the routine proceeds to step 23.

In step 23, the air compressor 21 is stopped. This prevents the air pressure Pc of the air tank 22 from exceeding the maximum set pressure P3.

In step 24, it is determined whether or not the air pressure Pc in the air tank 22 is equal to or lower than an appropriate dew point set pressure P2. If the air pressure Pc is not equal to or less than the appropriate dew point set pressure P2, "NO" is determined, and step 24 is repeated. on the other hand,
When the air pressure Pc becomes equal to or lower than the appropriate dew point set pressure P2, it is determined to be "YES", and the routine proceeds to step 25, where the air compressor 21 is driven again. Thereby, the air pressure Pc of the air tank 22 is maintained at the appropriate dew point set pressure P2 or more.

In step 26, it is determined whether or not the supply of the dry compressed air to the pneumatic device 4 is to be terminated. If the supply of the dry compressed air to the pneumatic device 4 is not to be terminated, the determination is “NO”, and the process proceeds to step S22.
Continue supplying dry compressed air to the.

On the other hand, when the supply of the dry compressed air to the pneumatic device 4 is to be terminated, “YES” is determined, and step 27 is performed.
Move to Subsequently, in step 27, the air compressor 2
1 is stopped, the inflow valve 25 and the outflow valve 26 are closed, and the dry air supply process is terminated in step 28.

Thus, according to the dry air supply device according to the embodiment of the present invention, the inflow valve 25 is provided on the inflow side of the membrane air dryer 23, and the outflow valve 26 is provided on the outflow side of the membrane air dryer 23. The controller 32 is provided with the air pressure detector 31
The air compressor 21, the inflow valve 25, and the outflow valve 26 are controlled based on the air pressure Pc of the air tank 22 detected by the above to perform the dry air supply processing. Can be supplied to the pneumatic device 4 while the pressure is set to at least the appropriate dew point set pressure P2.

That is, before the dry compressed air is supplied to the pneumatic device 4, the dry air supply device is operated idle for a predetermined time (idle operation time T). Air pressure Pc of tank 22 (inflow pressure of membrane air dryer 23)
Can be set and maintained within the range of the appropriate dew point set pressure P2 to the maximum set pressure P3.

Thus, in the preparation stage of supplying the dry compressed air to the pneumatic device 4, the film air dryer 23
The dew point of the dry compressed air generated by the film air dryer 23 can be set to be an appropriate dew point for the pneumatic device 4 (Steps 12 to 20). ).

More specifically, according to the dry air supply device according to the embodiment of the present invention, the inflow pressure of the membrane air dryer is greatly reduced as in the prior art.
The supply of the compressed air to the pneumatic device is performed, and it is possible to reliably prevent the supply of the compressed air having a high dew point containing a large amount of water to the pneumatic device. Further, as in the prior art, the inflow pressure of the membrane air dryer is lower than the allowable range of the inflow pressure of the membrane air dryer, and the drying action of the compressed air by the membrane air dryer is not exhibited at all. Can be reliably prevented. Further, as in the prior art, the inflow pressure of the membrane air dryer rises above the allowable range of the inflow pressure of the membrane air dryer, and an excessive inflow pressure acts on the membrane air dryer, and the The air dryer can be prevented from being damaged.

Further, according to the dry air supply device according to the embodiment of the present invention, the air pressure Pc of the air tank 22 is maintained at the appropriate dew point setting pressure P2 even while the dry compressed air is being supplied to the pneumatic device 4. To the maximum set pressure P3. Thus, during the supply of the dry compressed air, the regeneration of the dehumidifying film of the film air dryer 23 is reliably and appropriately performed, and the dry compression discharged from the film air dryer 23 toward the pneumatic device 4 is performed. The dew point of the air can be maintained to be appropriate for the pneumatic device 4 (steps 21 to 27). Therefore, the supply of dry compressed air having a dew point appropriate for the pneumatic device 4 can be maintained until the supply of dry compressed air is terminated.

Further, the dry air supply device according to the embodiment of the present invention has the following effects.

If the dry air supply device has not been used for a long time, moisture may adhere to the dehumidifying film of the film air dryer 23. In this case, in the dry air supply device according to the related art, when the dry air supply device is driven while moisture is attached to the dehumidifying film of the film air dryer, the moisture adheres to the dehumidifying film of the film air dryer. There has been a problem that moisture is discharged to the pneumatic device.

However, according to the dry air supply device according to the embodiment of the present invention, before the dry compressed air is supplied to the pneumatic device 4, the outflow valve 26 is closed and the film air dryer 23 is closed. Since the compressed air is supplied to the pneumatic device 4, the moisture adhering to the dehumidifying film of the film air dryer 23 can be reliably removed before supplying the dry compressed air to the pneumatic device 4. Therefore, it is possible to reliably prevent the moisture attached to the dehumidifying film of the film air dryer 23 from being discharged to the pneumatic device.

In the above embodiment, the air tank 2
2, an air pressure detector 31 is provided, and the air pressure detector 31 detects the air pressure in the air tank 22. However, the present invention is not limited to this, and the air pressure detector 31 is connected to the air tank 22 and the inflow valve 25. May be provided in the air pipe 24 between the two to detect the air pressure flowing into the film air dryer 23.

[0075]

As described in detail above, according to the first aspect of the present invention, an air compressor for supplying compressed air, an air tank for storing compressed air supplied from the air compressor, and the air tank A membrane air dryer for drying the compressed air flowing out of the membrane air dryer, an on-off valve provided between the inflow side of the membrane air dryer and the air tank, and an air pressure flowing into the membrane air dryer. An air pressure detector to be detected, and whether the air pressure detected by the air pressure detector is equal to or higher than an appropriate dew point set pressure, and closing the open / close valve when the air pressure is smaller than the appropriate dew point set pressure,
When the inflow pressure of the film-type air dryer becomes equal to or higher than the appropriate dew point setting, the pressure from the air tank is reduced. Air can be supplied to the membrane air dryer.

Thus, the dew point of the dry compressed air generated by the membrane air dryer can be made appropriate for a pneumatic device or the like, and the dry compressed air having an appropriate dew point is always supplied to the pneumatic device or the like. Can be supplied.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a dry air supply device according to an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a relationship between an inflow pressure of a membrane air dryer and a dew point of dry compressed air.

FIG. 3 is a flowchart showing a dry air supply process of the dry air supply device according to the embodiment of the present invention.

FIG. 4 is a flowchart showing a dry air supply process following FIG. 3;

FIG. 5 is a flowchart showing a dry air supply process following FIG. 4;

FIG. 6 is a circuit diagram showing a dry air supply device according to the related art.

FIG. 7 is a sectional view showing a membrane air dryer.

[Explanation of symbols]

 21 air compressor 22 air tank 23 membrane air dryer 25 inflow valve (open / close valve) 31 air pressure detector 32 controller (valve control means)

Claims (1)

[Claims] An air compressor for supplying compressed air; an air tank for storing compressed air supplied from the air compressor; a membrane air dryer for drying compressed air flowing out of the air tank; An on-off valve provided between the inflow side of the membrane air dryer and the air tank, an air pressure detector for detecting air pressure flowing into the membrane air dryer, and an air pressure detected by the air pressure detector Is determined to be above the appropriate dew point set pressure,
A dry air supply device comprising: valve control means for closing the on-off valve when the pressure is lower than the appropriate dew point set pressure, and opening the on-off valve when the pressure exceeds the appropriate dew point set pressure.