JP2000079093A - Air feeding instrument for endoscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To discharge air of various discharge pressures in pulses, stably discharge air for a specified period, and adjust the air discharge pressure immediately in response to a set pressure when changed. SOLUTION: In an air feeding instrument 15 for an endoscope, a compressor 13, an air tank 34, an air filter 35, a pressure control valve 38, a pressure sensor 14, and a discharge valve 12 are provided to form a closed space. By opening a main valve 12, air is discharged out of the closed space through an air tube AT11 and a connection port 11. When a pressure measured by the pressure sensor 14 is higher than a set pressure, the compressor 13 is not actuated, but the pressure control valve 38 is opened to reduce the pressure in the closed space. On the contrary, when the measured pressure is lower than the set pressure, the pressure control valve 38 is not opened, but the compressor 13 is actuated to increase the pressure in the closed space.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air supply device for an endoscope for sending air (air) into a body cavity such as a stomach, and more particularly to pressure control of discharged air.

[0002]

2. Description of the Related Art Conventionally, there has been known an endoscope air supply device capable of discharging air pressurized by a compressor by opening and closing a valve, and sending the discharged air into a body cavity through a tube or the like. Have been. In such an air supply device, a pressure control valve is provided to control the pressure of the discharged air, and the pressure of the discharged air is controlled by adjusting the cross-sectional area of the passage through which the air flows. .

[0003]

However, since the pressure control valve can only reduce the pressure of the discharged air, it is necessary to provide a high-output large compressor capable of supplying high-pressure air. Therefore, at the time of surgery, a noise problem is caused by the compressor that is constantly operating. Further, the conventional endoscope air supply device cannot discharge minute pressure air due to the structure of the pressure control valve, and performs accurate air pressure control corresponding to a wide range from low pressure to high pressure. Can not do.

[0004] On the other hand, there have been proposed inspection methods for examining the hardness of a foreign body in a body cavity such as a tumor by applying air to the foreign body, and examining the sensory threshold of an organ in the body cavity by applying air to the body. However, to perform such an inspection,
Needs an endoscope air supply device that can discharge air in a pulsed manner, stably discharge air for a certain period of time, and adjust air discharge pressure instantly when the set pressure is changed Becomes

According to the present invention, air having various discharge pressures can be discharged in a pulsed manner or can be stably discharged for a certain period of time, and when the set pressure is changed, the air can be discharged instantaneously. An object of the present invention is to provide an endoscope air supply device capable of adjusting a discharge pressure.

[0006]

SUMMARY OF THE INVENTION According to the present invention, there is provided an endoscope air supply apparatus comprising: a compressor for compressing air and sending the compressed air to a closed space; an air tank forming a part of the closed space; Pressure sensor, a pressure control valve for discharging air in the closed space to adjust the pressure in the closed space based on the pressure measured by the pressure sensor, and a discharge valve for discharging air in the closed space to the outside And characterized in that:

The closed space is formed by using a compressor, a discharge valve, and a pipe through which air passes between the compressor and the discharge valve, and an air tank having a capacity larger than the total capacity of the pipe is provided in the middle of the pipe. Is desirable.

The closed space includes a compressor, a first air tube connecting the compressor and the air tank, an air tank, a second air tube connecting the air tank and the air filter, an air filter, a third air connecting the air filter and the discharge valve. A tube, a fourth air tube connecting the third air tube and the pressure control valve, a pressure control valve,
A fifth air tube connecting the air tube and the pressure sensor,
Desirably, it is formed by a pressure sensor and a discharge valve.

The third air tube, the fourth air tube, and the fifth air tube are desirably connected by a joint.

Preferably, the compressor does not operate when the pressure in the closed space is higher than the set pressure, and operates when the pressure in the closed space is lower than the set pressure.

It is desirable that the pressure control valve be opened when the pressure in the closed space is higher than the set pressure and closed when the pressure in the closed space is lower than the set pressure.

It is desirable that the pressure in the closed space is checked to see if it matches the set pressure by comparing a voltage signal sent from the pressure sensor with a voltage signal corresponding to the set pressure.

The air discharged from the discharge valve is desirably sent into the body cavity through an air tube connecting the discharge valve and the connection port, the connection port, and a tube in the endoscope.

It is desirable that the discharge valve discharges air from a closed space in conjunction with an operation of depressing a foot pedal.

It is desirable that the discharge valve discharges air in a pulsed manner or stably discharges air for a certain period.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of an endoscope air supply device according to an embodiment of the present invention.

On the front side of the endoscope air supply device 15, an operation panel S provided with switches for performing operations such as pressure setting, a main switch 26, and connection ports 11 and 24 are provided. I have.

The main switch 26 is an endoscope air supply device 1.
5 is a switch for supplying power to the electric circuit No. 5.
The discharge switch 22 is a switch for discharging the air in the closed space formed in the endoscope air supply device 15 to the outside of the closed space. Air is discharged. The lamp 27 indicates that the ejection preparation is completed when the air in the closed space reaches a predetermined pressure. On the display unit 28, the air pressure to be set is displayed numerically.

The pulse switch 29 is a switch for pulsing the air to be discharged, and the one-second switch 30 is a switch for discharging the air for one second. The up switch 31 and the down switch 32 are switches provided for setting the pressure of the discharged air.

A connection tube 16 is connected to the connection port 11, and when air is discharged, air is sent into the body cavity through the connection tube 16. The connection port 24 has a foot switch 25 for enabling remote control of air discharge.
Power cord is connected.

One end of the connection tube 16 not connected to the connection port 11 is connected to a forceps port inlet 17 of the endoscope 20. The forceps port inlet 17 communicates with the forceps port outlet 19 through the forceps channel 18. A passage for passing air is formed between the connection port 11 and the forceps port outlet 19, and the air discharged from the connection port 11 is supplied to the forceps port outlet 1.
It leaves 9 and is sent into the body cavity. When an image of a body cavity is formed on an image sensor (not shown) provided in the endoscope 20, a moving image is displayed on a monitor (not shown) via the processor 21.

FIG. 2 is a rear view of the endoscope air supply device 15. A DC fan 47 for sending air to cool the inside of the endoscope air supply device 15 and an AC inlet 46 for receiving power from a commercial power source are provided.

FIG. 3 is an arrangement diagram of main components when the inside of the endoscope air supply device 15 is viewed from above (excluding electric circuits and wiring). An AC inlet 4 is provided on the wall of the housing 10.
6, DC fan 47, main switch 26, display unit 28
, And a connection port 24 are disposed.

A closed space for discharging air is formed inside the housing 10. This closed space is the compressor 1
3, air tube AT5 (first air tube), air tank 34, air tube AT4 (second air tube),
Air filter 35, air tube AT6 (third air tube), joint 36, air tube AT7 (fourth air tube), pressure control valve 38, air tube AT8
(Third air tube), fitting 37, air tube AT
9 (fifth air tube), a pressure sensor 14, an air tube AT10 (third air tube), and a discharge valve 12, and the air in the closed space is air tube A.
It is discharged from the connection port 11 via T11.

The closed space is branched in the direction of the pressure control valve 38 by the joint 36 and the air tube AT7, and similarly branched in the direction of the pressure sensor 14 by the joint 37 and the air tube AT9. However, the joint 36 connects the air tube AT6, the air tube AT7, and the air tube AT8, and the joint 37 includes the air tube AT8, the air tube AT10, and the air tube A.
T9 is connected. Each air tube is a tube through which air passes.

The air in the closed space is sent out of the closed space when adjusting the pressure and discharging the air. The pressure control valve 38 is opened to release air when reducing the pressure in the closed space, but is closed otherwise.
The discharge valve 12 is always closed except when the discharge switch 22 or the foot switch 25 is operated.

A silencer 33 for reducing noise when the compressor is operating is connected to an air inlet (not shown) of the compressor 13 via an air tube AT3. When the compressor 13 operates, the air entering through the silencer 33 and the air tube AT3 is compressed and sent into the closed space, thereby increasing the pressure in the closed space.

The air tank 34 is provided to increase the volume of the closed space.
It is sufficiently larger than the total capacity of the air tubes AT5 to AT10. In the air tank 34, connection ports 34a, 34 to which the air tube AT4 and the air tube AT5 are attached.
b is provided at a symmetrical position and the air tube AT
Reference numeral 5 is attached to the connection port 34a which is farther from the compressor 13 among the two connection ports.

The air filter 35 is provided for removing dust present in the closed space. The pressure in the closed space is
It is measured by the pressure sensor 14.

The pressure control valve 38 is operated so that the pressure in the closed space becomes a set pressure, thereby adjusting the pressure in the closed space. When it is determined that the pressure of the closed space measured by the pressure sensor 14 is lower than the set pressure,
The compressor 13 operates and the pressure control valve 38 closes. If it is determined that the pressure in the closed space is higher than the set pressure, the compressor 13 does not operate and stops, and the pressure control valve 38 opens. When the pressure in the closed space matches the set pressure, the compressor 13 does not operate and stops, and the pressure control valve 38 closes.

The discharge valve 12 operates when the discharge switch 22 or the foot switch 25 is operated.
When the discharge valve 12 opens, air is discharged from the connection port 11 via the AT 11.

FIG. 4 is a block diagram showing an electric circuit of the embodiment.

The control circuit 39 comprises a signal processing circuit 51, a voltage comparison circuit 52, a set pressure regulator 53, and a CPU 54, and controls the entire endoscope air supply device 15. The CPU 54 sends drive signals to the piezoelectric buzzer 49, the lamp 26, the compressor 13, the pressure control valve 38, and the discharge valve 12.

The operation panel switch section 48 includes a discharge switch 22, a pulse switch 29, a one-second switch 30,
A signal is generated by operating the up switch 31 and the down switch 32. Signals generated in the operation panel switch unit 48 and the foot switch 25 are sent to the CPU 54 via the signal mediation block 50. In the signal mediation block 50, predetermined processing of each signal transmitted from the operation panel switch 48, conversion to a signal that can be handled by the CPU 54, and the like are performed. A signal related to the pressure set by operating the up switch 31 and the down switch 32 is sent to the display unit 28 via the signal mediation block 50.

The signal output from the pressure sensor 14 is input to a signal processing circuit 51, where signal processing such as noise removal is performed. The processed signal is supplied to the voltage comparison circuit 52
Is input to On the other hand, based on the signal relating to the set pressure input to the CPU 54 by operating the up switch 31 and the down switch 32, a digital signal is output to the set pressure regulator 53.
(D / A converter). The digital signal is converted into an analog signal by the set pressure regulator 53 and sent to the voltage comparison circuit 52.

In the voltage comparison circuit 52, the signal processing circuit 51
Is compared with the signal (voltage signal) sent from the set pressure regulator 53. The compared signal is the CPU
The signal is converted into a signal that falls within the range of the voltage level that can be processed in 54 and sent to the CPU 54. The CPU 54 determines whether the pressure in the closed space matches the set pressure based on the signal sent from the voltage comparison circuit 52.

In order to prevent a hunting operation in which the operation, stop and opening and closing operations of the compressor 13 and the pressure control valve 38 occur repeatedly when the voltages compared in the comparison voltage unit 52 are substantially equal, the range of the comparison voltage is limited. Is provided with a dead voltage band.

The piezoelectric buzzer 49 emits a buzzer sound related to a switch operation. The lamp 27 indicates that the preparation for air discharge is completed.

Power is supplied to a power supply circuit (not shown) via the AC inlet 46 and the main switch 26, and the display unit 28, the pressure sensor 14, the CPU 5
4. Power is supplied to the air compressor 13, the pressure control valve 38, and the discharge valve 12 so as to correspond to respective predetermined voltage values.

FIG. 5 is a state transition diagram relating to air discharge.

When the main switch 26 is turned on,
First, an initial setting for the pressure in the closed space is performed (reference S1).
01), the set pressure is displayed on the display unit 28. Then, a pressure control operation is performed according to the initially set pressure (reference S102). The pressure control operation will be described later.

When the up switch 31 or the down switch 32 is operated, the value of the signal in the set pressure regulator 53 changes (reference S103). The set pressure changed according to the value of the changed signal is displayed on the display unit 28 (reference S
104), a pressure control operation is executed according to the changed set pressure (reference S102).

When the pressure in the closed space matches the set pressure by the pressure control operation, the lamp 27 is turned on to indicate that air can be discharged (reference S105).
The standby state is set until the foot switch 25 or the discharge switch 5 is turned on. If the pressure in the closed space fluctuates during the standby state, the pressure control operation is performed again (reference S).
102).

When the foot switch 25 or the discharge switch 22 is turned on during the standby state of the air discharge, the mode of the discharged air is determined (reference S10).
6). The mode of the discharged air is set in advance to either the pulse mode or the one-second mode by operating the pulse switch 29 or the one-second switch 30. When the pulse mode is set, for example, the discharge valve 12 is set so that the air discharge time is about 60 (msec).
Is opened and closed, thereby discharging air (reference S
107). When the one-second mode is set, the discharge valve 12 is opened and closed so that the air discharge time is one second, for example, and the air is discharged (reference S10).
8). When the air is discharged from the closed space, the pressure control operation returns to the original state and the pressure control operation is executed (reference S102).

FIG. 6 is a detailed state transition diagram of the pressure control operation in FIG.

First, it is determined whether the pressure in the closed space matches the set pressure (reference S201). When the pressure in the closed space is lower than the set pressure, the pressure control valve 38 is closed (reference S202), and the compressor 13 operates (reference S203). It is determined whether or not the pressure in the closed space matches the set pressure while the compressor 13 is operating (reference S204).
In a closed state 8, the compressor 13 continues to operate.

When the pressure in the closed space coincides with the set pressure, the compressor 13 stops operating (reference S20).
5). Then, it is determined again whether or not the pressure in the closed space matches the set pressure (reference S201), and if they match, the pressure control operation ends.

Conversely, when the pressure in the closed space is higher than the set pressure, the compressor does not operate and is stopped (reference S206), and the pressure control valve 38 is opened (reference S).
207). It is determined whether or not the pressure in the closed space matches the set pressure when the pressure control valve 38 is open (reference S2).
08), the pressure control valve 38 remains open until they match.

When the pressure in the closed space matches the set pressure, the pressure control valve 38 is closed (reference S20).
9). Then, it is determined whether or not the pressure in the closed space matches the set pressure when the pressure control valve 38 is closed (reference S).
201), if they match, the pressure control operation ends.

The above-described pressure control operation is executed until the pressure in the closed space matches the set pressure.

FIG. 7 is a diagram showing the pressure control operation, the pressure in the closed space during the air discharge, and the air discharge state over time. Here, the air discharge state is the air discharge state at the forceps port outlet 19 of the endoscope 20.

At time T0, the compressor 13 starts to operate, and the pressure in the closed space increases. When the pressure in the closed space reaches level 1 at time T1, the compressor 13 stops operating. The pressure range between level 1 and level 2 is
This is a pressure range corresponding to the dead voltage band set to suppress the hunting operation.

At time T2, the discharge valve 12 is opened and closed by operating the foot switch 25 or the discharge switch 22. However, the ejection air mode is set to the pulse mode, and the ejection periods T2 to T3 are set to 60 (mse).
c). The pressure drops instantly when the air is discharged,
Lower than level 2. As a result, the compressor 13 is activated immediately, whereby the pressure rises again.

The discharge valve 12 is closed at time T3. When the pressure of the closed space reaches level 1 again at time T4, the compressor 13 stops.

When the set pressure of the closed space is changed to level 3 at time T5, the compressor 13 starts operating.
However, the level 3 pressure is higher than the level 1 pressure.
At time T6, when the pressure in the closed space reaches level 3, the compressor 6 stops. The pressure range between level 3 and level 4 is a pressure range set for preventing hunting operation.

At time T7, the discharge valve 12 is opened by operating the foot switch 25 or the discharge switch 22.
As a result, air is discharged. At the same time as the air is discharged, the pressure in the closed space starts to decrease instantaneously and becomes lower than level 4. Therefore, the compressor 13 starts operating immediately, and the pressure in the closed space starts to increase. When the pressure in the closed space reaches the level 3 again at time T8, the compressor 13 stops operating. The air discharge pressure A is lower than the air discharge pressure B.

When the set pressure inside the closed space is changed to level 5 at time T9, the pressure control valve 38 is opened, and the pressure is reduced. When the pressure reaches level 5 at time T10, the pressure control valve 38 closes. Level 5
The pressure range between the level and the level 6 is a pressure range set for preventing the hunting operation.

FIG. 8 is an enlarged view of a partial range of FIG. The conditions 1, 2 and 3 respectively correspond to the air tank 34
Are small, medium, and large, respectively.

At time T2, the discharge valve 12 opens,
The pressure of the discharged air increases from pressure point 0 to pressure point 4.
At time T3, since the discharge valve 12 is closed, no air is discharged and the pressure drops to the pressure point 1.

In the discharge period T2 to T3, the state of the discharge pressure differs depending on the capacity of the air tank 34. When the capacity of the air tank is small, that is, in the condition 1, the discharge pressure immediately drops, and reaches the pressure point 0 during the discharge periods T2 to T3. On the other hand, when the capacity of the air tank is medium, that is, when the condition 2 is satisfied, the discharge pressure drops only to the pressure point 2 immediately before the discharge valve 12 closes. Further, when the capacity of the air tank is large, that is, in the condition 3, the discharge pressure drops only to the pressure point 3, and the discharge pressure in the discharge periods T2 to T3 is substantially constant.

Here, the relationship between the discharge pressure of air and the volume of the closed space will be described. For simplicity, it is assumed that the pressure in the closed space is constant and the volume of the closed space is substantially equal to the volume of the air tank 34.

The relationship between the volume and the pressure in a closed space is generally expressed by equation (1) (Boil's law). Here, it is assumed that the pressure is P, the volume is V, and no temperature change occurs.

P × V = const (constant) (1)

Assuming that all the air in the closed space is discharged when the air is discharged, the volume after the discharge of the air is equal to the total flow rate of the air discharged from the forceps port outlet 19. Therefore, assuming that the volume and the pressure before the air is discharged are P ₀ and V ₀ , respectively, and the volume and the pressure after the air is discharged are V ₁ and P ₁ , from the equation (1), P ₀ × V ₀ = P ₁ × V ₁ = P ₁ × Q × T (2) Here, Q is the flow rate of air discharged per unit time, and T is time.

It has been empirically obtained that there is a linear relationship between the discharge pressure of the air and the total flow rate Q × T of the discharged air. The higher the discharge pressure of the air, the higher the volume after the air is discharged. V ₁ increases. Since the pressure P ₀ is constant and the pressure P ₁ is equal to the atmospheric pressure, there is a linear relationship from the equation (2) between the discharge pressure of the air and the volume V ₀ of the closed space before the air is discharged. Understand.

[0066] The relationship between the discharge pressure and volume V ₀ which such air, in order to discharge the high constant time pressure air, it is necessary to increase the volume V ₀ which the closed space. That is, in order to stably discharge air having various discharge pressures for a certain period, it is necessary to increase the capacity of the air tank 34 as much as possible.

For example, when the discharge pressure of the air is set at 10 (mmHg) and the discharge is performed for one second, it is calculated how much the volume V _{0 of the} closed space is necessary. Assuming that the discharge pressure of the air is 10 (mmHg), the total flow rate Q × T of the discharged air is obtained from an empirical formula and is 65 (cc). If the pressure P _{0 of the} closed space is about 1.5 times the atmospheric pressure P ₁ , the required volume V of the closed space is V
₀ becomes V ₀ ≒ 40 (cc) from the equation (2). Assuming that the rate of decrease in the air volume after the air is discharged is suppressed to 10% or less, the air tank 34 has V ₀
It is sufficient that the volume is about 10 times that of the above, that is, the capacity is about 400 (cc). In this embodiment, an air tank 34 having a capacity of 1000 (cc) is further provided by multiplying by a safety factor.

As described above, according to the present embodiment, the operation and stoppage of the compressor 13 and the opening and closing of the pressure control valve 38 are performed based on the pressure of the closed space measured by the pressure sensor 14, so that the closed space is formed. The pressure can be adjusted to a set pressure, and the discharge valve 12
By opening the opening, air can be discharged into the body cavity.
In addition, as soon as the set pressure is changed, the pressure in the closed space is correspondingly adjusted, thereby adjusting the air discharge pressure.

Further, by discharging the air from the closed space state, the air can be discharged in a pulsed manner, and by providing the large capacity air tank 34, the air can be discharged stably for a certain period of time.

Since the compressor 13 is not operating at all times, the risk of noise problems is reduced, and the power consumption of the compressor 13 is reduced. Air tube AT5
Is attached to the connection port 34 a far from the compressor 13, so that the vibration of the compressor 13 is less likely to be transmitted to the air tank 34. Further, since there is no need to constantly send a large amount of air into the closed space, the size of the compressor 13 can be reduced.

Since air can be discharged by operating the foot pedal 25, air can be applied to the affected part in the body cavity while operating the endoscope 20 during surgery.

The one-second switch 30 is a switch indicating that air is discharged for one second, but the fixed period is not limited to one second.

The air tank 34 may be arranged between the air filter 35 and the discharge valve 12. That is, the air tank 34 can be disposed in the middle of any of the air tube AT6, the air tube AT8, and the air tube AT10.

[0074]

As described above, according to the present invention, air of various discharge pressures can be discharged in a pulsed manner, or air can be discharged stably for a certain period, and the set pressure can be changed. And the air discharge pressure can be adjusted instantaneously.

[Brief description of the drawings]

FIG. 1 is a perspective view of an endoscope air supply device according to an embodiment.

FIG. 2 is a rear view of the endoscope air supply device according to the embodiment.

FIG. 3 is a plan view of the inside of the endoscope air supply device as viewed from above.

FIG. 4 is a block diagram showing an electric circuit of the endoscope air supply device.

FIG. 5 is a state transition diagram of air discharge.

6 is a state transition diagram of the pressure control operation in FIG.

FIG. 7 is a diagram showing the state of air discharge and the pressure in a closed space over time.

FIG. 8 is an enlarged view of a partial range of FIG. 7;

[Explanation of symbols]

 Reference Signs List 12 discharge valve 13 compressor 14 pressure sensor 34 air tank 38 pressure control valve AT5 air tube (first air tube) AT4 air tube (second air tube) AT6 air tube (third air tube) AT7 air tube (fourth air tube) AT8 air tube (third air tube) AT9 air tube (fifth air tube) AT10 air tube (third air tube)

Claims (10)

[Claims] A compressor that compresses air and sends the compressed air into a closed space; an air tank that forms a part of the closed space; a pressure sensor that measures a pressure in the closed space; and a pressure sensor that measures a pressure measured by the pressure sensor. A pressure control valve that discharges air in the closed space to adjust the pressure in the closed space based on the pressure, and a discharge valve that discharges air in the closed space to the outside. Endoscope air supply device. 2. The closed space is formed by using the compressor, the discharge valve, and a pipe through which air is connected between the compressor and the discharge valve, and a total capacity of the pipe in the middle of the pipe. The air supply device for an endoscope according to claim 1, wherein the air tank having a larger capacity is provided. 3. The closed space includes the compressor, a first air tube connecting the compressor and an air tank, the air tank, a second air tube connecting the air tank and an air filter, the air filter, and the air filter. A third air tube connecting the filter and the discharge valve;
A fourth air tube connecting the third air tube to a pressure control valve; a pressure control valve; a fifth air tube connecting the air tube to a pressure sensor; the pressure sensor; and the discharge valve. The air supply device for an endoscope according to claim 1, wherein: 4. The air supply device for an endoscope according to claim 3, wherein the third air tube, the fourth air tube, and the fifth air tube are connected by a joint. 5. The method according to claim 1, wherein the compressor does not operate when the pressure in the closed space is higher than a set pressure, and operates when the pressure in the closed space is lower than the set pressure. The air supply device for an endoscope according to claim 1. 6. The pressure control valve is open when the pressure in the closed space is higher than the set pressure, and is closed when the pressure in the closed space is lower than the set pressure. The air supply device for an endoscope according to claim 1, wherein: 7. Checking whether or not the pressure in the closed space matches the set pressure by comparing a voltage signal sent from the pressure sensor with a voltage signal corresponding to the set pressure. The air supply device for an endoscope according to claim 1, wherein: 8. The air discharged from the discharge valve is fed into a body cavity through an air tube connecting the discharge valve and a connection port, a connection port, and an air tube in an endoscope. Item 7. An air supply device for an endoscope according to Item 1. 9. The air supply device for an endoscope according to claim 1, wherein the discharge valve discharges air in conjunction with an operation of depressing a foot pedal. 10. The endoscope air supply device according to claim 1, wherein the discharge valve discharges air in a pulsed manner or stably discharges air for a predetermined period.