JPS6314654B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention is applicable to liquid fuels such as kerosene and light oil, water, chemical liquids,
The present invention relates to an atomizing device for a liquid such as recording ink, and more specifically, to a so-called ultrasonic atomizing device that utilizes ultrasonic vibrations of an electric vibrator such as a piezoelectric vibrator.

Conventionally, various types of atomization devices have been proposed as ultrasonic atomization devices.

The most common atomization device is a horn-type ultrasonic atomization device.

This atomization device attaches a piezoelectric vibrator to a horn-type ultrasonic vibrator, uses a horn to amplify the vibration of the piezoelectric vibrator, and supplies liquid to the maximum amplitude surface at the tip of the horn using a pump, etc. It is something that becomes. However, in order to guarantee and maintain a stable resonance state of the horn oscillator, this atomization device requires high processing precision and complicated fixing conditions, and requires a liquid supply pump, making the entire device large. It had no choice but to become more expensive and more expensive.

In addition, although the power required to obtain an atomization amount of about 20 c.c./min is 5 to 10 watts, the atomization performance, such as the particle size variation of the atomized particles and the atomization ability, is insufficient. It wasn't something.

The second type of ultrasonic atomizer is a so-called ultrasonic humidifier, which is equipped with a piezoelectric vibrator at the bottom of the liquid tank and irradiates and concentrates ultrasonic energy near the liquid surface. It forms a liquid column and uses a type of cavitation phenomenon at the liquid surface to atomize it.

This atomization device does not require a liquid supply means such as a pump, and has excellent atomization ability, but because it directly atomizes using the ultrasonic energy of a piezoelectric vibrator, it does not require a liquid supply means such as a pump. The energy was extremely large, requiring 50 to 60 watts to achieve an atomization rate of about 20 c.c./min. Moreover, since the ultrasonic vibration frequency requires a high frequency of 1 to 2 MHz, the drive circuit thereof is extremely expensive and the possibility of radio wave interference is extremely high.
Further, the stability of the atomization amount is extremely poor, and the atomization amount fluctuates significantly depending on the liquid temperature, liquid level height, and liquid physical properties, and compensation thereof is extremely troublesome and complicated.

The third ultrasonic atomization device has been used in ink atomization devices of inkjet recording devices in recent years, and has a configuration as shown in FIG.

That is, a nozzle 2 is provided at one end of the ink chamber 1 and a piezoelectric vibrator 3 is provided at the other end, and pressure waves caused by ultrasonic vibrations of the piezoelectric vibrator 3 are transmitted to the nozzle 2 to spray droplets 4 from the nozzle 2 into mist. It is something that becomes. This atomization device does not require a liquid supply means such as a pump, has extremely low power consumption, and can make the particle size of atomized droplets considerably small.
It was also highly uniform.

However, since the structure is such that the vibration of the piezoelectric vibrator 3 is transmitted to the nozzle 2 via the ink (liquid) in the ink chamber 1, if the liquid does not have an extremely small amount of dissolved air, the dissolved air will become bubbles due to so-called ultrasonic cavitation. This has the disadvantage that stable atomization cannot be maintained.

Common liquids contain large amounts of dissolved gas,
In order to atomize with this atomizer, it is necessary to remove dissolved gas, which is extremely troublesome and expensive.

The present invention aims to provide an atomizing device that eliminates the above-mentioned conventional drawbacks.

The first object is to provide an atomization device that is simple and compact in construction and therefore inexpensive.

The second objective is to realize an atomization device that has excellent atomization performance such as atomization ability, particle size variation, and atomization pattern, and has extremely low power consumption.

A third objective is to realize a highly versatile atomizing device that can atomize extremely stably even liquids containing a large amount of dissolved gas.

In order to achieve the above object, the present invention has the following configuration.

That is, it includes a pressurizing chamber for filling liquid, a nozzle provided facing the pressurizing chamber, a vibrating body that vibrates the nozzle, and an electric vibrator that energizes the vibrating body, At least a portion of the vibrating body is configured to face the pressurizing chamber, and the vibrating body is configured to vibrate substantially in a fundamental vibration mode with respect to the pressurizing chamber. A portion of the vibrating body facing the pressurizing chamber vibrates without generating vibration nodes to vibrate the nozzle and spray droplets from the nozzle.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a sectional view showing the configuration of a hot air fan to which an atomizing device according to an embodiment of the present invention is applied as a kerosene atomizing device.

In FIG. 2, an operating section 6 is mounted on the top surface of the outer case 5
is provided to give an operation command to the control section 7.

The control unit 7 starts the blower motor 8, and the blower fan 9 is started. Therefore, the combustion air flows through the intake port 10.
It is sucked in as shown by the arrow in the figure, and the orifice 1
1 is sent to the swirler 13 through the negative pressure generating section 12. Further, the swirling air is sent from the swirler 13 to the atomization chamber 14 as a swirling airflow as shown by the arrow in the figure, and is exhausted through the combustion chamber 15 and the exhaust pipe 16.

On the other hand, kerosene is passed from the tank 17 through the pipe 18 to the leveler 1 that controls the liquid level to the position shown at A in the figure.
Sent to 9th. The leveler 19 is communicated with the atomizing section 21 through a pipe 20, and the atomizing section 21 is further communicated with the negative pressure generating section 12 through a pipe 22.

The liquid level inside the pipe 20 is at position B in the figure when the operation is stopped, and it matches the control liquid level A of the leveler 19, but the negative level that occurs due to the flow of combustion air due to the activation of the blower fan 9 The kerosene is sucked up by the negative pressure (for example, −20 to 30 mmH ₂ O) of the pressure generating portion 12 and fills the atomizing portion 21, and further rises to reach the liquid level position c in the pipe 22.

The above operation is completed in about 3 to 5 seconds after the operation command is given, and the atomization section 21 is filled with kerosene and preparations for starting atomization are completed.

Next, the control section 7 starts up the built-in drive circuit of the atomization section 21 and supplies the alternating current voltage as shown in FIG. 3 a, b, or c to the atomization section 21. The AC voltage supply form shown in figures a to c can be appropriately selected depending on the size of the amount to be atomized.

The atomization unit 21 is activated by the supply of this alternating voltage, and atomizes the atomization particles 23 into the atomization chamber 14 . The atomized particles 23 are mixed with the swirling airflow, ignited by the igniter 24, and ignited, and the flame is detected by the flame sensor 26. 27 is a convection fan.

In this way, a hot air fan to which an embodiment of the present invention is applied can be extremely simplified in configuration and have good controllability.

Next, the atomizing section 21 will be explained in more detail. FIG. 4 is a sectional view of the atomizing section 21, and the same symbols as in FIG. 2 are equivalent.

The atomizing section 21 is constructed by connecting pipes 20 and 22 to a body 29 which has a cylindrical pressurizing chamber 28 with a diameter of 10 to 15 mm and a depth of about 2 to 5 mm. It communicates with the pressurizing chamber 28 as shown in the figure. The body 29 is fixed to the wall surface of the atomization chamber 14 with screws 30 and 31.

32 is a piezoelectric vibrator having an outer diameter of 10 to 15 mm and a thickness of about 0.5 to 2 mm, and is an annular disk having a circular opening 33 in the center. Although not shown, electrodes are provided on both sides of the disk, and a third electrode is provided with lead wires 34 and 35.
The alternating current voltages shown in Figures a to c are supplied.

The piezoelectric vibrator 32 has an adhesive layer 36 with a thickness of 30 μm or more.
It is mutually bonded to the nozzle plate 37 with a diameter of about 100 μm, and the center part of the nozzle plate 37 has a diameter of 30 μm to
A plurality of nozzles 38 each having a diameter of about 100 μm are provided. Therefore, the nozzle plate 37 and the piezoelectric vibrator 32
are attached to each other and integrated to form an annular vibrating body. Since the piezoelectric vibrator 32 causes expansion and contraction strain in its radial direction as described later, this vibrating body can be considered as an annular disk-shaped asymmetric bimorph vibrating body. This vibrating body vibrates the central portion of the nozzle plate 37 (that is, the portion facing the opening 33 of the piezoelectric vibrator 32), and as a result, the nozzle 38 is vibrated. The nozzle plate 37 is further bonded to a fixing part 40 with an adhesive layer 39, and the fixing part 40 is attached to the body 29 with a threaded part 41 provided on its outer periphery.

Therefore, the piezoelectric vibrator 32 and the nozzle plate 3
The vibrating body consisting of 7 is fixed to the fixed part 40 and further fixed to the body 29 by screws.

When the piezoelectric vibrator 32 is applied with an alternating current voltage as shown in FIGS. 3 a to 3 c from the control unit 7 via the lead wires 34 and 35, it vibrates with expansion and contraction strain occurring in its radial direction. Therefore, the piezoelectric vibrator 32 and the nozzle plate 37
The vibrating body made of the above generates a flexural vibration of an annular disk whose periphery is fixed by the fixed part 40, and as a result, the central part of the nozzle plate 37 (the part facing the opening 33) is excited and flexurally vibrates. , the nozzle 38 is vibrated in its axial direction (horizontal direction in FIG. 4).

As a result, the atomized particles 23 can be sprayed from the nozzle 38. Reference numeral 42 indicates bubbles, which are generated by the vibration of the vibrating body, and are discharged into the pipe 22 as shown in the figure by the buoyancy of the bubbles due to the static pressure difference.

FIG. 5 is for explaining the vibration state of the above-mentioned vibrating body, and the same reference numerals as in FIG. 4 are equivalents.

FIG. 5 shows a case where the piezoelectric vibrator 30 is subjected to a reduction strain in the radial direction. As the droplet leaves the nozzle 38, the inside of the pressurizing chamber 28 is under negative pressure due to the vibrating body being strained as shown in the figure. However, the surface tension of the kerosene generated in the nozzle 38 prevents air from flowing into the pressurizing chamber 28 from the nozzle 38, and as a result, the kerosene is sucked up from the pipe 20, exerting a self-sufficient pump action.

Furthermore, if the piezoelectric vibrator 32 is strained in the opposite direction and expanded in the radial direction, it will be in a state as shown by the broken line in the figure.
As a result, a pressure increase near the nozzle 38 occurs, and the droplet 23 is ejected.

This operation is repeated according to the alternating current voltage as shown in Figure 3 a to c, so that the atomization pattern is stable, the particle size is small, and uniform atomization can be performed, and the amount of atomization can be easily adjusted. It can be used as a conversion device.
Furthermore, since it has the effect of sucking up kerosene, a liquid supply means such as a pump is not required.

As is clear from FIG. 5, the maximum point of pressure change in the liquid in the pressurizing chamber 28 is near the nozzle 38, and therefore, even if the liquid contains a large amount of dissolved air, the dissolved air due to ultrasonic cavitation is Since the liquid is injected from the nozzle 38 before the bubbles form, the generation of bubbles can be extremely reduced. Also, as shown in the figure, there may be slight air bubbles 42.
Although bubbles are generated in the pressurizing chamber 28, they grow into extremely large bubbles, and the nozzle plate 37 and piezoelectric vibrator 32
If the vibrator does not come into contact with the annular vibrating body, the atomizing operation will be hardly affected and an extremely stable atomizing operation can be achieved.

This is because, as long as the annular vibrating body made up of the nozzle plate 37 and the piezoelectric vibrator 32 performs the flexural vibration as shown in FIG. This is because, at least, no vibration nodes, ie, nodal circles, are generated on this annular vibrating body, and therefore, the air bubbles 42 do not come into contact with this vibrating body.

Of course, air bubbles 43 may accumulate at the joint between the nozzle plate 37 and the fixed part 39, that is, around the vibrating body, but in this case, unless extremely large bubbles accumulate, it will have an adverse effect on the vibration of the vibrating body. Moreover, even if the air bubbles 43 accumulate as shown in the figure, the static pressure distribution in the pressurizing chamber 28 and the buoyancy of the air bubbles 43 cause the pipe 2 to collapse before they grow into large air bubbles.
It will be discharged in 2nd place.

In this way, by configuring the vibrating body to vibrate in the fundamental mode in which no vibration nodes occur at least in the part of the annular vibrating body facing the pressurizing chamber 28, even liquids with a large amount of dissolved gas can be made extremely stable. Can be atomized.

However, if the vibrating body facing the pressurizing chamber 28 is vibrated in a higher order mode in which nodes are generated, the following problems will occur.

FIG. 6 is a sectional view of the atomizing section 21 for explaining the above-mentioned disadvantage, and the same reference numerals as in FIG. 5 are equivalent.

In FIG. 6, the nozzle plate 37 and the piezoelectric vibrator 3
As shown in the figure, nodes of vibration, that is, nodal circles, are generated in the portion of the annular vibrating body consisting of 2 facing the pressurizing chamber 28. In other words, the annular vibrating body vibrates in a higher order mode in which a nodal circle is generated near the center circle of the annular ring. If the opening at the center of the ring (corresponding to the opening 33 of the piezoelectric vibrator 32) is omitted and the vibration mode is shown as a disk modeled on the annular disk, the vibration state will be as shown in FIGS. 7a and 7b. FIG. 7a is a plan view thereof, and FIG. 7b is a cross-sectional view thereof, showing the second mode vibration of the disk deflection vibration. On the other hand, if the vibration state of the annular vibrating body shown in Fig. 5 is expressed as a vibration of a simple disk model, it becomes as shown in Fig. 8 a and b, which is considered to be the first mode of disk flexural vibration. As is clear from this explanatory diagram, it is important to vibrate the vibrating body in a vibration mode that does not produce nodal circles. When such a nodal circle occurs on the annular vibrating body facing the pressurizing chamber 28, the cavitation bubble 42 becomes the sixth
As shown in the figure, air bubbles 4 are attracted to the nodal circle.
4, and this bubble 44 is an annular vibrating body (overlapping part of the nozzle plate 37 and piezoelectric vibrator 32).
Growing up through contact with This is due to the sound pressure distribution within the pressurizing chamber 28 in such a vibration mode, and cannot be avoided as long as the annular vibrating body vibrates in such a mode. As the bubbles 44 grow larger, they significantly affect the vibration conditions of the annular vibrating body, making it difficult to maintain a stable vibration state, and eventually the vibrations stop completely and the spray from the nozzle 38 stops. will stop. Then, the bubbles 44 rise as shown by the arrow in the figure and are discharged into the pipe 22, and normal vibrations are excited again and spraying is restarted. Such a phenomenon appears as an irregular pulsation phenomenon in the spray state, resulting in instability of the atomization pattern and the amount of atomization.

The disadvantage caused by the bubbles 44 as described above is because the mechanical impedance of the vibrating body changes when the bubbles 44 touch the vibrating body (the annular portion consisting of the nozzle plate 37 and the piezoelectric vibrator 32). The above-mentioned inconvenience can be overcome by vibrating the vibrating body in a fundamental mode that does not produce any nodes. Furthermore, if air bubbles touch a part of the nozzle plate 37 other than the part constituting the annular vibrating body, the effect on the vibration of the vibrating body is small and does not cause much of a problem. This is thought to be because the effect of the annular vibrating body on the mechanical impedance is small, and this means that even on the annular vibrating body (the overlapping part of the piezoelectric vibrator 32 and the nozzle plate 37), there are no nodes. This means that no yen should be created.

In this way, as shown in FIG.
In order to perform stable spraying, it is extremely important to have a configuration in which the annular vibrating body facing 8 is vibrated in a fundamental mode in which no nodes occur.

FIG. 9 is a sectional view showing another embodiment of the atomizing device of the present invention, and the same reference numerals as in FIG. 6 are equivalent.
In FIG. 9, a nozzle plate 37 and a piezoelectric vibrator 30
The vibrating body itself is flexurally vibrating in a second-order mode in which nodal circles are generated, as shown in FIG. 6, and exhibits vibration states as shown in FIGS. 7a and 7b.

However, a sound wave blocking part 45 is provided between the pressurizing chamber 28 and the nozzle plate 37 as shown in the figure, and its tip 46 is configured to come into contact with a vibration node of the nozzle plate 37. Reference numeral 47 denotes a space, which allows parts other than vibration nodes to vibrate freely, and this may be filled with a sound wave absorbing material or the like. Also, nozzle plate 3
Although there is a gap between 7 and the tip 46 of the sound wave blocking part 45, since the pressurized chamber 28 is maintained at a pressure lower than atmospheric pressure, kerosene does not leak into the space 46, and the surface tension of the kerosene Due to this action, air does not flow into the pressurizing chamber 28.

With such a configuration, although the vibrating body itself operates in the secondary mode, the portion facing the pressurizing chamber 28 can apparently operate in the fundamental mode. That is, the vibrating body can be configured to vibrate in a substantially fundamental mode with respect to the pressurizing chamber 28. Therefore, as in the case of FIG.
It is possible to prevent the growth of air bubbles 44 due to the sound pressure distribution inside and to prevent them from coming into contact with the annular vibrating body made up of the nozzle plate 37 and piezoelectric vibrator 32, thereby achieving an extremely stable atomizing operation. Note that the bubble 43 is the fifth
As in the case shown in the figure, the particles are exhausted into the pipe 22 due to their buoyancy before they grow to the extent that they adversely affect vibration.

Therefore, even if the vibrating body itself operates in the secondary mode, stable atomization operation is possible by configuring it to vibrate in the fundamental mode with respect to the pressurizing chamber 28.

In this way, it is possible to realize an atomization device that can exhibit excellent atomization performance by using an atomization device such as the embodiment shown in FIG. 5 or FIG.
Furthermore, the energy required for atomization can be significantly reduced. According to the inventor's experiments, the power consumption is extremely low, and the power consumption required to obtain an atomization amount of about 20c.c./min is about 0.1W, making it extremely energy-saving compared to conventional ultrasonic atomization devices. It is possible to realize a high atomization device.

As described above, according to the present invention, there is provided a pressurizing chamber filled with liquid, a nozzle provided facing the pressurizing chamber, a vibrating body that vibrates the nozzle, and an electric current that energizes the vibrating body. the vibrating body is configured such that at least a part of the vibrating body faces the pressurizing chamber, and the vibrating body is configured to vibrate in a substantially fundamental mode with respect to the pressurizing chamber. is extremely simple, compact, and therefore low-cost, and has excellent atomization pattern stability, atomization performance,
It is possible to realize an atomization device that has excellent atomization performance such as particle size variation, can easily control the amount of atomization, and has extremely low power consumption. Furthermore, since the nozzle is configured to vibrate, it is possible to maintain the atomization operation even for liquids containing a large amount of dissolved gas, and in particular, the configuration is such that the vibrating body vibrates in a substantially fundamental mode relative to the pressurized chamber. Therefore, it is possible to realize a highly stable atomizing operation, and an extremely versatile atomizing device can be provided.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the configuration of a conventional ultrasonic atomization device, Fig. 2 is a sectional view of a hot air fan to which an embodiment of the present invention is applied, and Fig. 3 a, b, and c show the amount of atomization. 4 is a cross-sectional view of an atomizing device showing an embodiment of the present invention, FIG. 5 is an explanatory diagram of the operation of the atomizing device, and FIG. Cross-sectional view of the atomization device used to explain the invention, No. 7
Figures a and b are diagrams illustrating the operating state of the vibrating body of the atomizing device in Figure 6, Figures 8 a and b are diagrams explaining the operating state of the vibrating body of the atomizing device in Figure 5, and Figure 9
The figure is a sectional view of an atomizing device showing another embodiment of the present invention. 28... Pressure chamber, 32... Electric vibrator (piezoelectric vibrator), 33... Opening, 30, 37... Vibrating body (piezoelectric vibrator, nozzle plate), 38... Nozzle.

Claims (1)

[Scope of Claims] 1. A pressurized chamber filled with liquid, one or more nozzles provided facing the pressurized chamber, a vibrating body that vibrates the nozzle, and a vibrating body that energizes the vibrating body. an electric vibrator, at least one of the vibrating bodies
The atomizer is configured such that a portion thereof faces the pressurizing chamber, and the vibrating body is configured to vibrate in a substantially fundamental vibration mode with respect to the pressurizing chamber. 2. Claim 1 provides that the nozzle is provided on a nozzle plate, the electric vibrator is constituted by a plate-shaped piezoelectric vibrator, and the piezoelectric vibrator is attached to the nozzle plate to form the vibrating body. The atomization device described. 3. The piezoelectric vibrator is composed of a disk-shaped piezoelectric vibrator having a circular opening, and the disk-shaped piezoelectric vibrator is mounted on the nozzle plate so that the nozzle faces the opening, and the vibrating body is shaped like a ring. 3. The atomizing device according to claim 2, wherein the atomizer is a vibrating body and is configured such that the vibration of the annular vibrating body becomes a flexural vibration of an annular disk.