JPS6321541B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an atomization device for atomizing liquid fuels such as kerosene and diesel oil, water, and liquids such as medical solutions, and more specifically, relates to an atomization device that uses ultrasonic vibrations such as piezoelectric vibrators. This relates to a so-called ultrasonic atomization device.

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

The most typical first ultrasonic atomizer is a horn-type ultrasonic atomizer. In this method, a piezoelectric vibrator is attached to a horn vibrator, and the vibration amplitude is amplified by a liquid, and the liquid is supplied by a pump or the like to the maximum amplitude surface of the horn tip to atomize it.

The second ultrasonic atomization device is one that has been put into practical use in humidifiers, etc., and is equipped with a piezoelectric vibrator at the bottom of the liquid tank.
Ultrasonic waves are irradiated and concentrated near the liquid surface to form a liquid column, which is atomized using capillary waves near the liquid surface.

Furthermore, as a third ultrasonic atomization device, there is one having a configuration as shown in FIG. This atomization device is
In recent years, it has been used to atomize ink in recording devices such as facsimiles. The pressure increase in the liquid chamber 1 caused by this is transmitted to the orifice 2, and the liquid droplets 4 are ejected from the orifice 2 and atomized.

However, these conventional atomizing devices have the following drawbacks.

The first ultrasonic atomization device requires high machining accuracy of the amplitude amplification horn and complicated installation conditions, and also requires a pump, which makes the entire device larger and more expensive. Although the power required for atomization is large at about 10 watts for an atomization amount of about 20 c.c./min, the particle size and particle size of the atomized particles are uniform. The so-called atomization performance such as properties was not sufficient.

In addition, the second atomization device is characterized in that it can obtain atomized particles with a significantly small particle size and does not require a pump, but it uses an atomization method using ultrasonic energy directly irradiated into the liquid. Therefore, variations in atomization characteristics due to the physical properties of the liquid and the height of the liquid level are extremely significant, and compensation for this is extremely troublesome and extremely difficult. Furthermore, in order to obtain an atomization amount of 20 c.c./min at a high frequency of 1 to 2 MHz, a large amount of power of about 50 watts is required, which not only requires an expensive drive circuit but also causes radio interference. It has the disadvantage of being easy to occur.

Furthermore, the third atomizing device has a simple and compact configuration, and has the characteristics of extremely low power consumption. Since the structure is such that the pressure increase is transmitted to the orifice 2, bubbles are generated due to cavitation when using a general liquid containing a large amount of dissolved air, making it impossible to maintain a stable atomization operation. Therefore, only liquids from which dissolved air has been removed can be stably atomized, and can only be used for special purposes.

The present invention provides an atomizing device that eliminates the above-mentioned conventional drawbacks.

The first objective is to provide an atomizing device that is simple in construction, compact, and inexpensive.

The second object is to provide a highly versatile atomizing device that can stably atomize even general liquids containing a large amount of dissolved air.

A third object is to provide an atomization device that consumes extremely low power, has excellent atomization performance, and is capable of generating a large amount of atomized particles of uniform and fine particle size.

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

That is, the nozzle plate includes a pressurizing chamber filled with liquid, a nozzle plate having a plurality of nozzles facing the pressurizing chamber, and an electric vibrator that excites the bending vibration of the nozzle plate, and a protrusion on the nozzle plate. and the nozzle is provided on the protrusion, and the flexural vibration of the nozzle plate excited by the electric vibrator excites a plurality of nozzles with approximately equal amplitude, thereby producing a uniform and small vibration. Atomized particles having a particle size are injected from the nozzle and atomized.

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.

In FIG. 2, an operating section 6 is provided on the top surface of the warm air fan case 5, and is configured to give an operation command to a control section 7. When the control unit 7 receives an operation start command, it starts the blower fan motor 8, and the blower fan 9 and the pressure fan 10 rotate. This allows combustion air to flow from the suction port 11 to the orifice 1.
2 to the swirler 13, and from the swirler 13, it is supplied to the atomization chamber 14 and the combustion chamber 15 as indicated by the arrow in the figure. Then, the air is exhausted from the exhaust pipe 16. For example, a negative pressure of -20 mmH ₂ O is generated in the negative pressure generating section 17 downstream of the orifice 12 .

Kerosene, which is a fuel, is sent from the tank 18 to the leveler 20 through the pipe 19, and the leveler 20 adjusts the liquid level A.
be controlled at a constant level.

The atomizer 21 is attached to the wall surface 22 of the atomization chamber 14, and communicates with the leveler 20 through a pipe 24 having a filter 23 at its tip, and with the inlet side 25 of the pressure fan through a pipe 26, respectively.

When the operation is stopped, the liquid level in the pipe 24 is at position B in the figure, but when the operation is started, the pressure fan 1
0, due to the rotation of the blower fan 9, the pressure fan 10
Due to the pressure difference between the inlet side 25 and the outlet side 27, for example, _-60mmH2O , which is the sum of _-40mmH2O and the negative pressure _-20mmH2O generated in the negative pressure generating part 27,
The liquid level B rises, filling the atomizer 21 with kerosene, and rises further until it reaches the position of the liquid level C in the pipe 26 and balances out. In this way,
The inside of the atomizer 21 is filled with kerosene during pre-purging by the blower fan 9, and preparation for the atomization operation is completed.

Next, the control unit 7 energizes the built-in atomizer drive circuit and starts the igniter 28, so that the atomized particles 29 are sprayed from the atomizer 21 into the atomization chamber 14. The atomized particles 29 are ignited by the igniter 28 and burned to form a flame 30.

The combustion state of the flame 30 is detected by the sensor 31, and this signal causes the igniter 28 and the atomizer 21 to be activated.
The amount of atomization is controlled by the control section 7. Note that 32 is a convection fan.

Next, the atomizer 21 will be explained in more detail. FIG. 3 is a sectional view of the atomizer 21, and the same symbols as in FIG. 2 are equivalent.

The atomizer 21 has a depth of 2 to 5 mm and a diameter of 8 to 12 mm inside.
A body 34 having a pressurizing chamber 33 of mm is attached to a case 3.
5 with screw 36, and fix case 35 with screw 3.
It is fixedly attached to the wall surface 22 at 7 and 38. The pressurizing chamber 33 is provided with a supply port 39 and an exhaust port 40 facing each other vertically, and connected to the pipes 24 and 2, respectively.
It communicates with 6. One surface of the pressurizing chamber 33 is provided with a spherical protrusion 41 in the center, and this protrusion 41 has a
A nozzle plate 43 having a thickness of 30 μm to 100 μm and provided with a plurality of nozzles 42 having a diameter of 30 μm to 100 μm is attached. A ring-shaped piezoelectric vibrator 45 with a diameter of 8 to 12 mm and a thickness of 0.5 to 2 mm is mounted on this nozzle plate 43, and has an opening 44 in the center. It is designed to face the 44th.

The piezoelectric vibrator 45 is connected to electrodes (not shown) on both sides of the piezoelectric vibrator 45 via lead wires 47 and 48 as shown in FIG.
An alternating current voltage as shown in FIG. When a positive half-cycle voltage is applied, the piezoelectric vibrator 45 contracts diametrically, resulting in the nozzle plate 4
3 is deflected in the direction of the pressurizing chamber 33, the nozzle 42 is also displaced in the same direction, and the minute droplet 29 is ejected from the nozzle 42. On the other hand, during the negative half cycle, the piezoelectric vibrator 45 expands in the radial direction, and the nozzle plate 43 is deflected in the opposite direction. At this time, air inflow from the nozzle 42 is blocked by the surface tension of the kerosene generated therein, and as a result, a pressure drop occurs in the pressurizing chamber 33 corresponding to the increased volume. Therefore, kerosene is sucked up from the pipe 24, functioning as a self-sufficient pump.

In this way, the droplets 29 are ejected in accordance with the frequency of the AC voltage applied to the piezoelectric vibrator 45 (for example, 30 KHz to 100 KHz), and a corresponding amount of kerosene is self-sufficient.

The atomization amount q can be adjusted extremely easily and finely by performing intermittent control as shown in FIG. 4b. Figure 5 shows this situation.
By controlling the ratio α between T ₁ (operating time) and T ₂ (repetition time), the atomization amount q can be adjusted with very good linearity.

6a and 6b explain the operation of the atomizing device shown in FIG. 3 in more detail, and the same reference numerals as in FIG. 3 correspond to the same parts. FIG. 6a shows the vibration state of the nozzle plate 43 and the piezoelectric vibrator 45, and the scattering state of the atomized particles 29, and FIG. 6b shows the distribution of the vibration amplitude δ at this time. As is clear from the figure, the vibration amplitude δ of the protruding portion 41 is approximately constant, and the amplitude of only this portion is significantly larger than that of the other portions. This is a spherical protrusion 41
This is because the protrusion 41 acts as a rigid body by providing the flat part 4.
6, which has a rigid body in the center, is flexibly vibrating. By providing a plurality of nozzles 42 on the protrusion 41 that can be treated as a substantially rigid body, the vibration amplitude δ of the plurality of nozzles can be made substantially uniform. The relationship between the vibration amplitude δ of the nozzle 42 and the atomized particle diameter d is approximately proportional as shown in FIG. This shows that the atomized particle diameter d can be made uniform.

FIGS. 8a and 8b show the nozzle plate 43 as in this embodiment.
This figure shows the vibration state and atomization state when the protrusion 41 that can be considered as a rigid body is not provided, and the vibration amplitude distribution δ of each part.
and the same symbols are equivalents. As is clear from comparing FIGS. 8a and 8b with FIGS. 6a and 6b, when there is no protrusion 41 that can be considered a rigid body, the
The vibration amplitude δ of each of the two is completely different, as shown in FIG. 8b. For this reason, atomized particles having extremely non-uniform particle sizes, such as atomized particles 29 in FIG. 8a, are generated.

In this way, the nozzle plate 43 is provided with a protrusion 41 that can be regarded as a substantially rigid body, a plurality of nozzles 42 are provided on the protrusion 41, and the nozzle plate 43 is deflected and vibrated to produce mist with uniform and minute particle size. It is possible to generate a large amount of particles.

As shown in FIGS. 6a and 6b, the maximum point of pressure change in the pressurizing chamber 33 is near the nozzle 42, and the atomized particles 29 are injected only by the pressure increase in the very vicinity of the nozzle 42. Due to this structure, even liquids containing an extremely large amount of dissolved air, such as kerosene, can be stably atomized. This is because, as mentioned above, the maximum pressure change is near the nozzle 42, so cavitation bubbles are ejected from the nozzle 42 before they grow.
Even if bubbles form, the area within the pressurized chamber 33 that affects the spray is a narrow area very close to the nozzle 42, so they will immediately pop out from this area and be discharged from the exhaust port 40. , it hardly affects the atomization operation.

9, 10, and 11 are cross-sectional views of an atomizing device showing other embodiments of the present invention, and the same reference numerals as in FIG. 6a correspond to the same ones. In FIG. 9, the protrusion 41 is formed into a plateau shape, and a plurality of linear droplet arrays having a uniform particle size can be generated to obtain a large amount of atomization.

FIG. 10 shows a projection 41 having a conical shape, which makes it possible to obtain a so-called hollow cone atomization pattern and to obtain uniform atomized particles.

FIG. 11 shows an atomization pattern that is a combination of the atomization patterns shown in FIGS. 9 and 10, in which nozzles 42 are provided at the top and slope of the protrusion 41.

As described above, the atomizing device of the present invention can be implemented in various ways, but as is clear from the principle of its atomizing operation, it is configured to vibrate the nozzle, so the vibration energy for the atomizing operation is reduced. It is possible to obtain an atomization device with extremely high utilization efficiency and extremely low power consumption. According to experiments, the power consumption of the piezoelectric vibrator 45 required to atomize approximately 20 c.c./min of kerosene using the atomizing device of the embodiment shown in Fig. 3 is 0.1.
The power consumption is only a few % or less compared to conventional ultrasonic atomizers.

As described above, according to the present invention, there is provided a pressurizing chamber filled with liquid, a nozzle plate provided with a plurality of nozzles facing the pressurizing chamber, and an electric vibration that excites bending vibration in the nozzle plate. Since the nozzle plate is provided with a protrusion, and the nozzle is provided on the protrusion, the structure is extremely simple and compact, and therefore the cost is low, and a large amount of dissolved air can be generated. It is possible to provide an extremely versatile atomizing device that can stably atomize even liquids containing liquids. In particular, since a protrusion is provided and a nozzle is installed in this protrusion, it is possible to generate a large amount of atomized particles with a uniform and small particle size, and it is possible to exhibit excellent atomization performance. It is possible to provide an atomization device that has low power consumption and is highly energy-saving.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the configuration of a conventional atomization device.
Fig. 2 is a sectional view showing the configuration of a hot air fan to which an atomization device according to an embodiment of the present invention is applied, Fig. 3 is a sectional view showing the detailed configuration of the atomization device, and Figs. 4a and 4b are The oscillating voltage waveform diagram of the piezoelectric vibrator, FIG. 5 is a characteristic diagram explaining the method of controlling the atomization amount q, and FIGS. 6 a and b are sectional views explaining the vibration state of the atomization device in FIG. Vibration amplitude distribution diagram, Figure 7 is a characteristic diagram explaining the correlation between vibration amplitude δ and atomized particle diameter d, and Figures 8a and b are a cross-sectional diagram and vibration amplitude distribution diagram showing the vibration state of the embodiment of the present invention, respectively. , FIG. 9 is a sectional view showing another embodiment of the atomization device of the present invention, FIG. 10 is a sectional view showing still another embodiment of the same, and FIG. 11 is a sectional view showing still another embodiment of the same. It is. 33... Pressure chamber, 41... Projection, 42... Nozzle,
43... Nozzle plate, 44... Opening, 45... Electric vibrator (piezoelectric vibrator), 46... Flat part.

Claims (1)

[Claims] 1. A pressurizing chamber filled with a liquid, a nozzle plate facing the pressurizing chamber and provided with a plurality of nozzles, and an electric vibrator that energizes the nozzle plate and excites flexural vibration, and the nozzle An atomizing device comprising: a plate provided with a protrusion; and the protrusion provided with the nozzle.