JPS5812064B2 - Ultrasonic atomizer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a vibration magnifying horn coupled to an ultrasonic transducer.
The ultrasonic atomizer vibrates by the vibration of the vibrator and atomizes the liquid supplied to the atomization surface of the horn, such as liquid fuel for combustion, liquid paint for painting, etc. It relates to a liquid supply passage bored in the horn for supplying liquid.

The most common ultrasonic atomization device conventionally used will be explained based on FIG. 4.

Reference numeral 1 denotes an ultrasonic vibrator with a vibrating element 2 inserted therein, and a vibration amplifying horn 3 is connected to one end of the ultrasonic vibrator.

A liquid supply passage 4 is bored inside the vibration magnifying horn 3. One end of the liquid supply passage 4 communicates with a part of the atomization surface 5 through an opening 6, and the other end communicates with a portion of the atomization surface 5 through an opening 6. At position 7, it is connected to a conduit 9 via a vibration isolator 8.

The other end of conduit 9 communicates with a liquid tank (not shown) via a flow regulator (not shown).

10 and 11 indicate corners formed inside the liquid supply passage 4, respectively.

In the ultrasonic atomization device as described above, vibration is started,
When the liquid is sent, atomized particles 12 are released from the atomizing surface 5 as shown in FIG. 5, but at the same time, a large number of fine bubbles 13 are generated from the inner circumferential surface and corners 10 and 11 of the liquid supply passage 4. In addition, fine bubbles 1 are also formed due to cavitation caused by liquid vibration.
Generates 4.

These fine bubbles 13 and 14 accumulate at positions where the forces of the liquid flow rate and the vibration are balanced, forming a bubble group 15.

As time passes, the fine bubbles 13 within the bubble group 15 combine with each other, and finally form a large bubble 1 as shown in FIG.
6, and when it reaches the size of the large bubble 16, the force received by the flow of liquid becomes stronger, and the large bubble 16 is pushed toward the opening 6, and when it reaches the opening 6, the seventh bubble 16 is formed.
As shown in the figure, the supply of liquid to the atomization surface 5 is stopped by the cavities of the air bubbles 16, resulting in interruptions in the atomization particles 12.

As described above, the most common ultrasonic atomization device that has been used conventionally has a major problem in that continuous atomization cannot be performed due to the occurrence of interruptions.

Therefore, if this ultrasonic atomizer is incorporated into a combustion device, it will cause a misfire due to breaks in atomization, making it useless and dangerous; , problems such as uneven coating occur.

The present invention provides an ultrasonic atomization device that does not cause interruptions in atomization and does not have any complicated structure. Examples thereof will be described below.

1 and 2 show an ultrasonic atomizer, and FIG. 3 shows a combustion device equipped with the atomizer shown in FIGS. 1 and 2. Since the same reference numerals as those in FIGS. 7 to 7 indicate the same members, their explanations will be omitted.

Reference numeral 4' indicates a liquid supply passage, the inner peripheral surface of which is processed by reaming and has a smooth surface with a surface roughness of about 25 μm.

Note that 25 μm indicates the depth of the unevenness on the inner surface of the liquid supply passage 4', thereby indicating the state of the smooth surface.

As shown in FIG. 2, 17 and 18 are smooth corners formed by removing the protruding corners on the inner surface of the liquid supply passage 4' with appropriate curvature.

Reference numeral 1 denotes an ultrasonic vibrator with a vibrating element 2 inserted therein, and a vibration amplifying horn 3 is connected to one end of the ultrasonic vibrator.

The inside of the vibration magnifying horn 3 has an inner peripheral surface with a surface roughness of approximately 2.
A liquid supply passage 4' with a smooth surface of 5 μm is formed, one end communicates with a part of the atomization surface 5 through an opening 6, the other end communicates with a conduit 9, and a solenoid valve 19 and a flow rate adjustment device. 20 to a fuel tank (not shown).

Reference numeral 21 denotes an inner cylinder, which is disposed so as to concentrically surround the vibration amplifying horn 3. On the circumferential surface of the inner cylinder 21, a single cylinder is used to take in primary combustion air and air for cooling the ultrasonic vibrator 1. Alternatively, it has a plurality of air intake ports 22, and a vibration magnifying horn support 24 is fixed to one end via a vibration damping material 23.

The vibration magnifying horn 3 is fixed to a vibration magnifying horn support 24.

A radial air agitator 25 is attached to the other end of the inner cylinder 21, and the radial air agitator 25 is connected to a secondary air passage 27 formed by an outer cylinder 26 and an inner cylinder 21, which are arranged concentrically with the inner cylinder 21. They communicate via a flow-type air agitator 25.

Reference numeral 28 denotes a front end face plate of the radial air atomizer 25, which is located almost on the same plane as the vibration atomizing surface 5.
The combustion chamber 30 is equipped with a combustion tube 29 having a diameter larger than the inner diameter of the combustion chamber 30.
It forms a compartment.

A partition plate 31 having a hole smaller than the inner diameter of the radial air disruptor 25 and larger than the front diameter of the vibration amplifying horn 3 is provided on the rear end surface of the radial air disruptor 25.
An annular gap 32 is formed between the two.

Reference numeral 33 denotes a blower, which is connected to the outer cylinder 26 via a blower port 34 that can send a tangential air flow into the secondary air passage 27.

Reference numeral 35 denotes a back cover, which is partially equipped with a flame detector 36.

37 is an ultrasonic oscillator, and 38 is a flange for attaching the combustion device.

Next, the operation of the ultrasonic atomizer shown in FIG. 1 will be explained.

When the vibration is started and the liquid is sent, the atomized particles 12 are released from the atomizing surface 5 as shown in FIG. Approximately 2 by threading
5 μm, the resistance is reduced at the boundary between the inner wall and the liquid, and the generation of fine bubbles 13 due to cavitation is extremely reduced, making it difficult for large bubbles 16 to be generated, and the conduit 9 does not vibrate due to the vibration isolating material 8. After all, cavitation does not occur, and therefore, no fine bubbles 13 are generated.

Next, the smoothing of the inner surface of the liquid supply passage 4 described above will be described in more detail.

As mentioned above, smoothing of the passageway 4' is accomplished by reaming.

Stainless steel, duralumin, aluminum, etc. are generally known as constituent materials of the horn.

The degree of smoothness of the liquid supply passage 4' obtained by the above processing is measured by a stylus method, a cutting method, or the like.

However, in the stylus method, the needle is generally placed on the measurement surface and moved laterally, and the amount of upward and downward movement of the needle is measured. If the value is small, it is difficult to measure.

Therefore, a cutting method is used.

In this method, a mold material such as a synthetic resin is poured into the liquid supply passage 4', and after solidification, the mold material is taken out, cut, and its surface is observed under a microscope.

FIG. 8 shows the results of measuring the amount of bubbles generated by varying the roughness of the inner surface of the liquid supply passage 4' of the apparatus shown in FIG. 1.

Note that the amplitude of the atomization surface of the horn in this experiment was 15μ.
The m1 temperature was 15° C. The flow rate of the liquid in the liquid supply passage 4' was 12 CC/in.

As is clear from FIG. 8, when the surface roughness exceeds 25 μm, the amount of bubbles generated increases rapidly, which causes interruptions in the generation of atomized particles.

Note that it is technically extremely impossible to reduce the surface roughness to 3 μm or less.

Therefore, according to this experiment, when the surface roughness is in the range of 3 to 25 μm, the amount of bubbles generated is extremely small, and the generation of atomized particles is hardly interrupted.

FIG. 2 shows a corner portion 1 of an appropriate curvature in addition to the configuration of FIG.
7 and 18.

Therefore, it is possible to prevent the occurrence of cavitation at sharp corners, which occurs in the past, and no minute bubbles are generated, making it possible to more reliably prevent atomized particles from discontinuing compared to the configuration shown in Figure 1. .

Next, FIG. 3 will be explained.

Most of the air flow sent into the secondary air joint 27 from the blower 33 through the air outlet 34 flows toward the radial air disturbance body 25 while swirling inside the secondary air passage 27, and a portion of the air flows toward the radial air disturbance body 25. It passes through the intake port 22 and flows into the inner cylinder 21, and is further divided into primary combustion air and ultrasonic vibrator cooling air. The acoustic wave vibrator 1 is cooled, and the primary combustion air is
It is ejected into the combustion chamber 30 through an annular gap 32 formed by the partition plate 31 and the vibration amplifying horn 3.

The air flowing while swirling in the secondary air passage 27 is made uniform between the intermediate paths, is further given a strong swirl by the radial flow type air disruptor 25, and is ejected into the combustion chamber 30 as main combustion air.

On the other hand, the fuel reaches the atomizing surface 5 from the fuel tank (not shown) through the flow rate adjustment device 20 and the solenoid valve 19, through the conduit 9 and the liquid supply passage 4', and is transmitted to the atomization surface 5 by the ultrasonic oscillator 37 and the ultrasonic vibrator 1. The generated vibrations are amplified by the vibration amplification horn 3 and atomized.

It is atomized at surface 5.

Atomized fuel atomization particles have many problems that make them unsuitable for combustion, such as the particle speed being slow and the atomization pattern not being consistent, unlike the particles atomized by normal pressure spraying or air atomization. .

Therefore - second combustion. The atomization pattern is corrected by burning air, the fuel and combustion air are mixed by strong swirling of the main combustion air, and ignition and combustion are performed by an ignition device (not shown).

However, since the atomized particle group generated by ultrasonic vibration contains many large atomized particles, especially 10,000 particles are included.
In a flame with a combustion rate of Km/h or less, a large amount of particles will be scattered, and a large amount of carbon monoxide will be generated, resulting in a significant decrease in the combustion heat output. The particles are vaporized in the combustion tube 29 to achieve good combustion.

Here, if the amount of primary combustion air is too large, it may easily cause a misfire due to the flame being blown away, or it may worsen the mixing of the fuel and combustion air, resulting in the generation of soot.If it is too small, the tip of the vibration amplifying horn 3 The flames may cling to the parts and cause burnout, or the atomization pattern may become unstable, causing flame fluctuations, which may cause carbon to accumulate on the inner wall of the combustion tube 29.

Therefore, the minimum necessary primary combustion air can be stably taken in from the intake port 22 of the inner cylinder 21, and there is no need to extremely narrow the annular gap 32, so that sufficient light can be sent to the flame detector 36. In addition, since the vibration amplifying horn 3 performs ultrasonic vibration, the annular gap 32 can be widened, making assembly work easier.

The combustion amount can be easily changed by the flow rate adjustment device 20, and a predetermined amount is atomized on the atomization surface 5, but the atomization pattern also changes depending on the change in the flow rate.

The position of the atomization surface 5 is the front end face plate 28 of the radial air agitator 25.
If it moves too far toward the partition plate 31 side, the combustion atomized particles will hit the radial air disruptor 25, and the fuel will flow into the secondary air passage 27, and if it moves too far into the combustion chamber 30 from the front end face plate 28, the flame will become entwined. Therefore, by arranging the atomizing surface 5 at a position almost on the same plane as the front end face plate 15, it is possible to always maintain safety and high stability even if the combustion amount changes. can.

In addition, since the position of the atomization surface 5 and the strength of swirling of the combustion air flow are set to have an appropriate flame holding ability, if atomized fuel breaks, the combustion device may cause a misfire. However, by incorporating the above-mentioned ultrasonic atomizer, the atomized fuel will not be cut off, and misfires will no longer occur.

As described above, the ultrasonic atomization device of the present invention improves the surface roughness of the inner circumferential surface of the liquid supply passage bored inside the vibration amplifying horn.
The diameter is 25 μm or less, which prevents the formation of bubbles in the liquid supply passage and eliminates any interruption in atomization.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of an ultrasonic atomizer according to an embodiment of the present invention, Fig. 2 is a cross-sectional view showing a modification thereof, Fig. 3 is a cross-sectional view of a combustion device incorporating the same device, and Figs. FIG. 7 is a sectional view of a conventional device of this type, and FIG. 8 is a diagram showing the relationship between the amount of bubbles generated in the liquid supply passage and the surface roughness of the passage. 1... Ultrasonic vibrator, 3... Vibration magnifying horn, 4'... Liquid supply passage, 5...
Atomization surface, 17,1B... Corner.

Claims (1)

[Scope of Claims] 1. An ultrasonic transducer comprising an ultrasonic vibrator, a vibration amplifying horn coupled to the vibrator, and a liquid supply passage bored through the horn and supplying liquid to the atomization surface, the liquid supply passage having an inner surface. The surface roughness is 25
An ultrasonic atomization device characterized by having a smooth surface of μm or less. 2. The ultrasonic atomization device according to claim 1, wherein the inner surface of the liquid supply passage has a shape with an acute angle portion removed.