JPS6311063B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an atomization device for atomizing liquid fuels such as kerosene and light oil, water, chemicals, recording ink, etc. More specifically, the present invention relates to an atomization device for atomizing liquids such as kerosene and light oil, water, chemicals, and recording inks. The present invention relates to a so-called ultrasonic atomization device that atomizes liquid using ultrasonic vibrations of a piezoelectric vibrator such as a crystal.

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

The most typical conventional ultrasonic atomization device is
There is a horn type ultrasonic atomizer. In this type, a piezoelectric vibrator or magnetostrictive vibrator is attached to one end of a horn-shaped vibrator for increasing the amplitude, and liquid is supplied and dripped by a pump or the like to the other end of the vibrator for increasing the amplitude. It is atomized. This atomization device uses a horn-shaped vibrator made of duralumin etc. to ensure stable vibration, but its high processing accuracy,
In addition to requiring precise fixing conditions, it also requires a liquid supply device such as a pump, which makes the entire atomization device extremely large and expensive. Further, the atomization performance was not sufficient, and the particle size was relatively large and the variation in particle size was large. Furthermore, it requires 5 to 10 watts of power to obtain an atomization amount of about 20 c.c./min.
The drive circuit was also relatively expensive.

As the second ultrasonic atomizer, there is a so-called liquid column type ultrasonic atomizer. This atomization device has a piezoelectric vibrator installed on the bottom of the liquid tank, and directs ultrasonic energy of 1 to 2 MHz into the liquid, concentrating it near the liquid surface and atomizing the liquid through a type of cavitation phenomenon. It has been put into practical use, for example, in humidifiers. However, although this atomization device has excellent atomization properties, it is extremely difficult to stabilize the amount of atomization, and the amount of atomization depends not only on the physical properties and properties of the liquid, but also on the height of the liquid level, etc. The variation in chemical properties was remarkable. Furthermore, since it directly atomizes the particles using ultrasonic energy,
The energy required for atomization was extremely large, and the electric power required to obtain an atomization amount of about 20 c.c./min was extremely large, ranging from 40 to 60 watts. Therefore, 1~
The drive circuit for generating a drive power of 40 to 60 watts at 2MHz is also extremely expensive, and has the disadvantage of extremely large amounts of unnecessary radiation.

As a third ultrasonic atomizer, an atomizer as shown in FIG. 1 has been proposed. This is liquid chamber 1
An orifice 2 is provided at one end and a piezoelectric vibrator 3 is provided at the other end, and droplets 4 are ejected from the orifice 2 by the vibration of the piezoelectric vibrator 3 and atomized. It has been applied to This atomization device has a simple and compact configuration, does not require a liquid supply device such as a pump, can uniformly atomize particles with a particle size determined by the diameter of the orifice 2, and is extremely stable in the spray direction. The above feature is that the energy required for atomization is extremely small, but the pressure wave caused by the ultrasonic vibration of the piezoelectric vibrator 3 is transmitted through the liquid in the liquid chamber 1 to the orifice 2. Therefore, a low pressure point is generated in the liquid chamber 1, and a so-called cavitation phenomenon inevitably occurs. There is a considerable amount of air remaining in a transitory liquid, and if atomization is carried out using the device shown in Figure 1, the formation of dissolved air into bubbles due to the cavitation phenomenon described above will be extremely noticeable. Therefore, it has been impossible to maintain stable atomization operation. Therefore, the first
The atomization of the liquid by the device shown in the figure must be configured to be performed after removing air dissolved in the liquid, and the configuration of the atomization device is extremely troublesome. Due to this drawback, despite having the various advantages mentioned above, it is difficult to apply it widely, and only a limited number of practical applications have been carried out.

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

The first object is to provide an atomizing device which is extremely simple and compact in construction and therefore inexpensive.

The second objective is to provide an atomization device with extremely low power consumption and excellent atomization performance.

Furthermore, a third object is to provide an atomization device that can perform an extremely stable atomization operation even for liquids containing dissolved gases, and that can be easily applied to a wide range of applications.

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

That is, the piezoelectric vibrator includes a base body having a pressurized chamber for filling a liquid, a nozzle plate having a nozzle facing the pressurized chamber, and a piezoelectric vibrator attached to the nozzle plate and having an opening in the center. Electrodes are provided on the adhesive surface of the vibrator with the nozzle plate and on the surface facing the adhesive surface, and the piezoelectric vibrator is configured to vibrate in a transverse effect, and the piezoelectric vibrator is configured to face the nozzle plate or the base body and the adhesive surface. With this structure, it is possible to achieve the above objectives 1 to 3 and provide an atomization device that eliminates the conventional drawbacks. .

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 upper surface of a case 5 of the warm air fan, and is configured to give an operation command to a control section 7. Kerosene, which is a fuel, is sent from the cartridge tank 8 to a fixed tank 9 where the liquid level A is kept substantially constant. The fixed tank 9 is connected to the atomizing section 11 through a pipe 10.
is connected by a pipe 12 to a negative pressure generating section 13 provided in a part of the combustion chamber air passage. pipe 1
The liquid level B of kerosene in 0 is at the same level as the liquid level A when the operation is stopped, as shown in the figure.

When an operation start command is sent from the operation unit 6 to the control unit 7, the blower fan 14 that blows combustion air is started, and the combustion air is sent from the suction port 15 to the orifice 16.
through the first air passage 17 to the first air chamber 1
8, sent to the second air chamber 19. First air chamber 18
A vaporization mixing section 20 is provided around the second air chamber 19, and a combustion chamber 21 is provided around the second air chamber 19. Air is ejected from the swirling air flow holes 22 and flame holes 23, respectively, and the air flows as shown in the figure. It is configured so that it can be done. 2
4 is an exhaust hole. Also, part of the combustion air is
The air passes through the air path 25, is hot-aired by the heater 26, and sent to the swirler 27, generating a swirling hot-air flow in the first atomization chamber 28 as shown in the figure. When the blower fan 14 and heater 26 are started and a certain period of time has elapsed,
Because the positive pressure generated in the second atomization chamber 29 is applied to the liquid level A through the pipe 30, and the negative pressure generated in the negative pressure generation section 13 is applied to the atomization section 11 through the pipe 12, , the liquid level B rises and the inside of the atomizing part 11 is applied, and it rises to the position of the liquid level C in the pipe 11 and becomes balanced, and as a result, the inside of the atomizing part 11 becomes filled with kerosene. Next, the control section 7 starts the atomization section 11, and the atomization section 11 sprays the atomized particles 31 into the first atomization chamber 28 and the second atomization chamber 29. Atomized particles 31
is mixed with the hot air sent from the swirler 27, sent to the vaporization mixing chamber 20, where it is gasified, and the mixture is sent to the combustion chamber 21.
The premixed gas is sent to Then, it is ignited by the igniter 32 and combusts around the secondary air ejected from the flame port 23 to form a flame 33. 34
is a flame rod that detects the combustion state and can adjust the air-fuel ratio as necessary. The heater 26 is turned off when the temperature of the vaporization mixing chamber 20 becomes sufficiently high and the atomized particles 31 can be sufficiently gasified. A convection fan 35 sucks indoor air through an inlet 36 and discharges warm air through an outlet 37, as shown in the figure.

In this way, the oil combustion machine (warm air machine) to which one embodiment of the present invention is applied has an extremely simplified configuration.

Next, FIG. 2, which will explain the atomizing section 11 in more detail, is a sectional view showing a more detailed configuration of the atomizing section 11, and the same reference numerals as in FIG. 2 are equivalents.

In the atomizing part 11, a base body 39 having a pressurizing chamber 38 is fixed to a fixing part 40 with screws (not shown), and the fixing part 40 is fixed to the wall 43 of the second atomizing chamber 29 with screws 41 and 42. has been done. The pressurizing chamber 38 has a diameter of 10 to 15
It is a cylindrical room with a depth of about 1 to 5 mm, and has a supply port 44 and an exhaust port 45 with pipes 10 and 10, respectively.
It is connected to 12. A nozzle plate 46 with a thickness of about 30 μm to 100 μm is provided on one side of the pressurizing chamber 38,
A piezoelectric ceramic 49 having a diameter of 10 to 15 mm and a thickness of about 0.5 to 2 mm is attached to a mounting portion 47 of the nozzle plate 46 using an electrode 48 which also serves as an adhesive layer. In addition, the non-attached portion 50 of the nozzle plate 47 is made of piezoelectric ceramic 49.
The non-mounting part 50 is provided with a curved surface part 52. A plurality of nozzles 53 each having a diameter of approximately 30 μm to 100 μm are provided on the curved surface portion 52 , and the nozzles 53 face the pressurizing chamber 38 . The other electrode 54 is provided on the piezoelectric ceramic 49, and a lead wire 55 is soldered to the electrode 54. The lead wire 56 is connected to the fixing part 40 with a screw 41, and the nozzle plate 46
It is electrically connected to the electrode 48 via etc.
57 is an adhesive layer, and 58 is a sealing material.

Through the lead wires 55 and 56, the control unit 7 applies AC voltages as shown in FIGS. 4a to 4c to the piezoelectric ceramic 49 according to the amount to be atomized, and the ultrasonic vibrations of the piezoelectric ceramic 49 produce the atomization as shown in the figure. particle 3
1 spray atomization can be performed.

Next, the atomization operation will be explained.

A piezoelectric vibrator such as the piezoelectric ceramic 49 has two types of piezoelectric effects, called the longitudinal effect and the transverse effect, and those that cause strain in the polarization direction of the piezoelectric ceramic 49 are called the longitudinal effect and those that cause strain in the direction perpendicular to the polarization direction. What causes distortion is called a lateral effect.

The piezoelectric ceramic 49 shown in FIG. 3 has a donut-shaped disk structure as shown in FIG.
As shown in the figure, distortion occurs in response to an alternating current voltage, resulting in so-called radial vibration, and utilizes the transverse effect of the piezoelectric vibrator described above.

In other words, by utilizing the transverse effect, vibration parallel to the surface of the nozzle plate 46 can be generated with the electrode structure shown in FIG.

Since the nozzle plate 46 and the piezoelectric ceramic 49 are bonded, depending on the structure of the nozzle plate 46 and the driving frequency, the nozzle 53 is caused to vibrate in the radial direction, including flexural vibration as shown in FIG. It is excited in the direction. As a result, atomized particles 31 are ejected from the nozzle 53 as shown in FIG. By configuring the nozzle 53 to be vibrated by the vibration caused by the transverse effect of the piezoelectric vibrator in this way, the point of maximum change in pressure within the pressurizing chamber 38, that is, the point of maximum acceleration, becomes very close to the nozzle 53. Therefore, even liquids such as kerosene containing a large amount of dissolved gas can be stably sprayed. Therefore, the atomizing section 11 vibrates the piezoelectric ceramic 49 by vibration due to the transverse effect, thereby causing the nozzle 5 to repeat the state shown in FIG. 6 a or b and the opposite state.
3, resulting in axial vibration of nozzle 5.
The atomized particles 31 can be atomized from the pipe 10 and self-supplied from the pipe 10. Figure 6 a or b
In this state, the surface tension of the kerosene generated in the nozzle 53 prevents air from flowing in from the nozzle 53, causing a pressure drop in the pressurizing chamber 38, causing kerosene to be sucked up from the pipe 10, and the self-sufficient pump It plays the role of

Although it is possible to stably atomize kerosene by such vibrations as shown in FIG. Nozzle 53
produces a slight vibration along the axial direction of the Although it is not shown explicitly in FIGS. 6a and 6b because it is shown as a model, the actual axial width of the nozzle 53 and the maximum width of the mounting portion 47 are quite large, and therefore the above-mentioned The maximum acceleration point in the pressurized chamber 38 is concentrated in the vicinity of the nozzle 53,
Therefore, even liquids containing a large amount of dissolved air can be stably sprayed. That is, the vibration in the states shown in FIGS. 6a and 6b can be considered to be a transverse effect vibration of the piezoelectric ceramic 49 whose load is the deflection vibration of the non-mounted part 50, and therefore the vibration width along the axial direction of the nozzle 53 is Compared to this, atomization can be performed with the amplitude in the same direction of the piezoelectric ceramic 49 being sufficiently small, and therefore the above-mentioned effect can be obtained. However, the mounting portion 47 also has
Since there is a slight vibration along the axial direction of the nozzle 53 as shown in FIG. Even if bubbles are generated in the pressurizing chamber 38, the effect on the atomization characteristics is small, but it may be inconvenient in realizing an atomization device that does not allow even slight variations in the injection direction.

In order to prevent such inconveniences, the present invention can take the following configuration, and with this configuration, even general liquids containing a large amount of dissolved air can be sprayed extremely well. I found out that it is possible.

FIGS. 7a and 7b show the piezoelectric ceramic 49 in a case where the piezoelectric ceramic 49 is vibrated by a transverse effect with a configuration capable of achieving such a purpose.
This figure shows the state of vibration between the nozzle plate 46 and the non-attached portion 50 of the nozzle plate 46.

As is clear from FIGS. 7a and 7b, a piezoelectric ceramic 49 is attached to an adhesive layer 48 on a mounting portion 47 of a nozzle plate 46.
In the bonded state, the piezoelectric ceramic 49 vibrates almost only in its diametrical direction, while the non-attached portion 50 of the nozzle plate 46 vibrates in the axial direction of the nozzle 53, that is, flexural vibration. (The operations in Fig. 6 a, b are actually Fig. 7 a,
It can be considered that it is close to b. ) In this way, the piezoelectric ceramic 49 vibrates due to the transverse effect, and this vibration is used as an excitation source to cause the non-mounted part 50 of the nozzle plate 46 to flexurally vibrate, and as a result, the nozzle 53 is vibrated in its axial direction. With this configuration, the maximum point of pressure change in the pressurizing chamber 38 can be concentrated only in the vicinity of the nozzle 53, and as a result, kerosene can be injected from the nozzle 53 before cavitation bubbles are generated. The spraying operation of a liquid containing a large amount of dissolved gas can also be maintained extremely stably.

FIG. 8 is a block diagram for clarifying this excitation relationship. The piezoelectric ceramic 49 vibrates due to the transverse effect with the non-mounted part 50 of the nozzle plate 46 as a load, and the non-mounted part 50
9 shows that the nozzle 53 is subjected to flexural vibration in the axial direction by the excitation.

In order to achieve such a good vibration relationship, the resonant frequency of the transverse effect vibration of the piezoelectric ceramic 49 with the non-mounted part 50 as a load and the resonance frequency of the flexural vibration of the non-mounted part 50, which is the load, must be approximately equal to each other. It is extremely important to have the same configuration. By adopting such a configuration, the piezoelectric vibrator 49 vibrates only in the radial direction due to the transverse effect, and the non-mounted portion 50 of the nozzle plate 46 does not flex. As a result, the nozzle 53 is vibrated in its axial direction, and therefore, there are no points with large pressure fluctuations that would generate cavitation bubbles except in the immediate vicinity of the nozzle 53 in the pressurizing chamber 38. This makes it possible to achieve an extremely favorable atomization operation. Therefore, even a liquid such as kerosene containing a large amount of dissolved gas can be sprayed extremely stably.

FIG. 9 shows the resonance characteristics when the piezoelectric ceramic 49 has the structure shown in FIGS.
This shows the correlation between

When the piezoelectric ceramic 49 of this embodiment is configured as shown in FIG. 3 and the pressurizing chamber 38 is filled with kerosene, it exhibits resonance characteristics as shown in _{FIG .} It will have the following. From the relationship between frequency and current, the inventor has determined that
Although it seems that resonance point ₂ has better atomization characteristics than resonance point ₁ , in reality, resonance point ₁ shows better atomization characteristics, and as mentioned above, resonance point ₁ has better atomization characteristics than resonance point 1. The piezoelectric ceramic 4 is loaded with the deflection vibration of the non-mounted part 50 as shown in Figures a and b or Figure 7.
It was confirmed that this was the resonance of the transverse effect vibration of No. 9. In addition, ₂ in this case is piezoelectric ceramic 4
This is the resonance frequency of the flexural vibration of No. 9, and the spray characteristics at this time were not very good, and it was also confirmed at the same time that a relatively large number of bubbles were generated due to cavitation due to the above-mentioned reason.

Therefore, the piezoelectric ceramic 49 is
Alternatively, by configuring it to operate at a resonant frequency based on transverse effect vibration with the deflection vibration of the non-mounted part 50 as a load as shown in FIGS. In particular, as shown in FIGS.
It has become clear that more stable and better spraying can be achieved by operating the device in a configuration that matches the resonance frequency of the zero deflection vibration.

The atomization operation with such a configuration can be performed with extremely low power consumption; for example, the power consumption of the piezoelectric ceramic 49 required to obtain an atomization amount of about 20 c.c./min is about 0.1 Watt. . Moreover, since the particle size of the atomized particles 31 is determined by the diameter of the nozzle 53, the atomized particles can have a fine particle size with good uniformity, and the spray pattern is also stable. It has.

In addition, as mentioned above, the structure is extremely simple and compact, and since it is possible to self-supply kerosene, there is no need for a pump, etc., and the overall configuration of the atomization device is extremely simple, compact, and low cost. is possible.

As described above, according to the present invention, a piezoelectric vibrator is attached to a nozzle plate attached to a base such that the nozzle faces a pressurizing chamber, and electrodes are provided on the surface of the piezoelectric vibrator on which it is attached to the nozzle plate and on the surface opposite thereto. is provided, and the piezoelectric vibrator is configured to vibrate with transverse effect,
By applying an AC voltage between the electrode facing the mounting surface and the nozzle plate or base, the structure is extremely simple and compact, resulting in low cost, extremely low power consumption, and excellent atomization performance. can provide an excellent atomization device. In particular, even liquids containing a large amount of dissolved gas (air) can be sprayed extremely stably without being affected by cavitation, so there is no need for troublesome processes such as removing dissolved gas. Therefore, it is possible to provide an atomizing device that can easily and stably atomize various liquids. Therefore, its application range is extremely wide and its industrial value is extremely large.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing the configuration of a conventional ultrasonic atomizer, Fig. 2 is a cross-sectional view showing the configuration of a hot air fan to which the atomizer according to an embodiment of the present invention is applied, and Fig. 3 is a cross-sectional view showing the configuration of a conventional ultrasonic atomizer. 4a to 4c are drive voltage waveform diagrams corresponding to the atomization amount of the piezoelectric ceramic constituting the atomizer, and FIG. 5 is an external perspective view illustrating the strain direction of the piezoelectric ceramic. , Figures 6a and b are diagrams explaining the operation of the piezoelectric ceramic and the nozzle plate, Figures 7a and b are diagrams explaining the best operation of the piezoelectric ceramic and the nozzle plate, and Figure 8 is the diagram of the piezoelectric ceramic and the nozzle. Block diagram explaining the mutual relationship with the non-mounted part of the plate, No. 9
The figure is a diagram showing the current frequency characteristics of the same piezoelectric ceramic. 38... Pressurization chamber, 46... Nozzle plate, 47...
Mounting part, 49... Piezoelectric vibrator, 50... Non-wearing part, 51... Opening, 53... Nozzle.

Claims (1)

[Scope of Claims] 1. A base body having a pressurized chamber filled with liquid, a nozzle plate having a nozzle facing the pressurized chamber, and a piezoelectric vibrator attached to the nozzle plate and having an opening in the center. , electrodes are provided on a bonding surface of the piezoelectric vibrator to the nozzle plate and a surface facing the bonding surface, and the piezoelectric vibrator is configured to vibrate with a transverse effect, and the nozzle plate or the base body and the An atomization device configured to apply an AC voltage between an electrode facing the adhesive surface. 2. The frequency of the alternating current voltage is configured to be approximately equal to the resonant frequency of the transverse effect vibration of the piezoelectric vibrator, and
2. The atomization device according to claim 1, wherein the resonant frequency of the non-attached portion of the nozzle plate and the resonant frequency of the piezoelectric vibrator substantially match.