JPS6340593B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an atomization device for atomizing liquid fuels such as kerosene and light oil, water, liquid chemicals, recording ink, etc. In other words, the present invention relates to an atomization device that uses ultrasonic vibration to atomize liquid using ultrasonic vibration of an electric vibrator such as a piezoelectric ceramic.

Conventional configurations and their problems Conventionally, various configurations of this type of atomization device have been proposed.

For example, the configuration shown in FIG. 1a is the most typical one, in which a piezoelectric ceramic 2 is bonded to a horn 1 made of stainless steel or the like, and the vibration of the piezoelectric ceramic 2 is amplified by the horn 1. A pump 4 is used to supply liquid to the tip of the horn 1. The liquid 5 sent to the tip of the horn 1 generates a so-called capillary wave due to the vibration of the tip of the horn 1, and scatters as atomized particles 6 as shown in the figure.

As a conventional atomizing device shown in FIG. 2, there is one shown in FIG. 1b, in which a piezoelectric ceramic 8 is attached to the bottom of a liquid tank 7, and ultrasonic vibration energy is directly irradiated into the liquid. Ultrasonic energy irradiated into the liquid forms a liquid column 9 on the liquid surface as shown in the figure, and atomized particles 10 are scattered by capillary waves generated on the liquid surface.

The above first and second conventional atomization devices basically utilize capillary waves generated by ultrasonic vibration, although there are differences in the presence or absence of amplification during vibration.
This is a typical example of a so-called ultrasonic atomization device.

On the other hand, as a third conventional atomizing device that has been used in inkjet recording devices in recent years, the mechanism of atomization is different from the first and second conventional atomizing devices. There is a structure as shown in Fig. 1c. This has an orifice 12 at one end of the ink chamber 11, and a piezoelectric vibrator 1 at the other end.
3 and a diaphragm 14, the pressure wave caused by the vibration of the piezoelectric vibrator 13 is transmitted to the orifice 12, and the ink fine particles 15 are ejected from the orifice 12, and the ejected ink is A volume of ink corresponding to
It is configured to be automatically replenished from 6 onwards.

Although atomizing devices with various configurations have been proposed in the past, each of them has drawbacks as described below and has been limited to special uses.

The first atomization device does not have sufficient atomization performance, such as atomization performance of atomized particles, uniformity of particle size, and stability of atomization pattern, and furthermore, the liquid supply system using the pump 4 is extremely poor. It was troublesome. Furthermore, in order to ensure stable vibration of the horn 1, high machining accuracy and complicated fixing conditions for the horn 1 are required. For this reason, the entire device had to become larger and more expensive. Further, the power required to obtain an atomization amount of, for example, 20 c.c./min was as large as 5 to 10 watts.

Although the second atomization device does not require a pump or the like, since direct atomization is performed using ultrasonic waves, the atomization characteristics vary significantly depending on the physical properties of the liquid and the height of the liquid level, making compensation for this extremely difficult. Ta.

The power required for atomization is extremely large, 20c.c./min.
It required 50 to 100 watts to obtain the amount of atomization and required operation at an extremely high frequency of 1 to 2 MHz. Therefore, it has to be extremely expensive and has the serious disadvantage of being highly likely to cause radio wave interference.

Since the third atomization device does not atomize using so-called ultrasonic energy, the power required for atomization is extremely small and has a very compact configuration. Since the pressure increase in the ink is transmitted to the orifice 12 through the ink, the dissolved air in the ink becomes bubbles due to so-called cavitation, and stable atomization cannot be achieved. Therefore, it is necessary to use an ink that does not contain dissolved air, and therefore, it is extremely lacking in versatility.

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

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

The second purpose is to have excellent atomization performance such as atomization, uniformity of particle size, and stability of atomization pattern.
Moreover, it is an object of the present invention to provide an atomization device that has excellent controllability such as control of the amount of atomization and control of the timing of atomization.

A third object is to provide an atomization device that can stably atomize even a general liquid containing a large amount of dissolved air without being affected by cavitation.

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

That is, the flexible vibrating body includes a nozzle plate having a nozzle and a plate-shaped electric vibrator, and a body having a pressurizing chamber filled with liquid, and the flexible vibrating body faces the pressurizing chamber. is attached to the body, and the flexural vibrator is energized in a second or higher order flexural vibration mode in which the vibrations of the nozzle and the vibrations of the electric vibrator are substantially opposite in phase to each other. , the nozzle is configured to vibrate, and the vibration of the electric vibrator excites the flexural vibration of the flexural vibrator to vibrate the nozzle, and the liquid in the pressurized chamber is injected from the nozzle. and atomizes it.

DESCRIPTION OF EMBODIMENTS 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 warm machine to which an atomizing device according to an embodiment of the present invention is applied.

In FIG. 2, an operating section 18 is provided on the top surface of a case 17 of the warm air fan, and provides an operation command to a control section 19. When a command to start operation is given, the control unit 1
9 starts the blower fan motor 20, and the blower fan motor 20 starts the blower fan 21 and the suction fan 22.
Rotate. Therefore, the combustion air flows into the intake cylinder 23.
It is sucked in like an arrow, and the orifice 24,
It is sent to the flower 26 through the load generation section 25,
The swirling airflow is sent from the slurry 26 to the atomization chamber 27. Then, it is sent to the combustion chamber 30 through the flame holding port 29 and exhausted from the exhaust pipe 31.

On the other hand, kerosene is sent from the tank 32 via a pipe 33 to a leveler 34, and from the leveler 34 to an atomization section 35 via a pipe 36. The leveler 34 controls the liquid level of kerosene to a position A in the pipe 36 when the operation is stopped.

The discharge side of the suction fan 22 is connected to the negative pressure generation section 25 through a communication section 37, and the suction side is connected to the atomization section 35 through a pipe 38. Therefore, when the operation is started, the sum of the negative pressure (ΔP ₁ ) generated in the negative pressure generator 25 and the negative pressure difference (ΔP ₂ ) generated between both ends of the suction fan 22 (−ΔP=− ΔP ₁ −
ΔP ₂ ) is generated in the suction part 39, and this negative pressure (-
ΔP) is applied to the liquid level A in the pipe 36 via the pipe 38 and the atomizing section 35. As a result, the liquid level A in the pipe 36 rises, filling the atomizing section 35 with kerosene and becoming balanced with the liquid level B in the pipe 38. In this way, the inside of the atomizing section 35, which was empty when the operation was stopped, is filled with kerosene.

Next, the control unit 19 activates the built-in oscillator 40 to energize the atomizing unit 35 and activates the igniter 41. The atomized particles 43 are atomized, mixed with combustion air, and discharged from the flame holding port 29. Then, it is ignited by the igniter 41 and a flame 43
forms and burns. In addition, 44 is a flame sensor, 45
is a convection fan.

In this way, the hot air fan to which the atomizing device of one embodiment of the present invention is applied has an extremely simple configuration.

Next, the atomizing section 35 will be explained in more detail. FIG. 3 is a sectional view showing the detailed structure of the atomizing section 35, and the same reference numerals as in FIG. 2 are equivalent.

In FIG. 3, the atomizing section 35 has a diameter of approximately 5 to 15 mm.
Body 4 having a pressurizing chamber 46 with a depth of 2 to 5 mm
7 and a case 49 to which the body 47 is fixed with screws 48, and the case 49 is fixed to the wall surface 42 with screws 5051. A nozzle plate 52 is provided on one surface of the pressurizing chamber 46, and the outer periphery of the nozzle plate 52 is soldered to the body 47.
This nozzle plate 52 is made of a thin metal plate with a thickness of 30 μm to 100 μm, and a projection 53 is provided in the center, and the projection 53 has a diameter of 30 μm to 100 μm.
A plurality of 100 μm nozzles 54 are provided.

Furthermore, the nozzle plate 52 has a diameter of 5 to 15 mm and a thickness of 5 mm to 15 mm.
A disk-shaped piezoelectric vibrator 55 of 0.5 to 2 mm is soldered. An opening 56 is provided in the center of the piezoelectric vibrator 55, and a nozzle 54 faces the opening 56. Although not shown, electrode layers of approximately several micrometers are provided on both surfaces of the piezoelectric vibrator 55 (both left and right ends in the figure), and the nozzle plate 52 is soldered to the electrode layers. The piezoelectric vibrator 55 is a piezoelectric ceramic polarized in the direction of the electrodes, and the lead wires 57, 5
8, an alternating current voltage is supplied according to the amount to be atomized, as shown in FIG. 4a, b or c. Of course, the voltage supplied to the piezoelectric vibrator may not be an alternating current voltage but a direct current pulse voltage as shown in d and e of the figure.
According to the polarity of the supplied AC voltage, the piezoelectric vibrator 5
5 causes expansion and contraction strain in its radial direction, but this radial expansion and contraction strain is converted into flexural vibration because the nozzle plate 52 and the piezoelectric vibrator 55 are soldered.
That is, the nozzle plate 52 and the piezoelectric vibrator 55 form an asymmetric bimorph vibrating body, which becomes a flexural vibrating body. Therefore, the nozzle 54 is also vibrated in the left-right direction in the figure, and the kerosene in the pressurizing chamber 46 is injected from the nozzle 54 as atomized particles 43 and atomized. Since the particle size of the atomized particles 43 is determined by the diameter of the nozzle 54 and the repetition frequency and voltage magnitude of the AC voltage supplied to the piezoelectric vibrator 55, excellent uniformity and small atomization can be achieved. The atomization pattern also depends on the shape of the protrusion 53 and the nozzle 54.
The pattern can be set freely and is stable depending on the arrangement of the patterns. The generation timing of atomized particles and the amount of atomization can be controlled extremely easily and reliably by simply controlling the supply timing of AC voltage, as shown in Fig. 4 a to c, and the control is very good. It has controllability. The atomized particles 43 are sprayed when the nozzle 54 is displaced toward the pressurizing chamber 46 (to the right in FIG. 3), and when the nozzle 54 is displaced to the opposite side (to the left in FIG. 3), the nozzle 54 is pressurized. A volume of kerosene corresponding to the volume of the kerosene injected as atomized particles 43 is sucked up into the chamber 46 from the pipe 36 . This is because the surface tension of the kerosene generated in the nozzle 54 prevents air from flowing into the pressurizing chamber from the nozzle 54.

In this way, kerosene can be self-sufficient and atomized by simply supplying alternating current voltage to the piezoelectric vibrator 55.

As mentioned above, since the mechanism of the atomization operation does not utilize the capillary wave generated by ultrasonic energy, the power consumption of the piezoelectric vibrator 55 is extremely small, and an atomization amount of 20 c.c./min is obtained. The input power of the piezoelectric vibrator required is 0.1~
It is 0.2watts.

Next, the operation of the flexible vibrating body made up of the nozzle plate 52 and the piezoelectric vibrator 55 will be explained in more detail. In FIGS. 5a and 5b, the same symbols as in FIG. 3 are equivalent.

As shown by the broken lines in FIG. 5a and b, the vibration mode of the flexural vibrator is such that the vibration phases of the nozzle 54 and the piezoelectric vibrator 55 are opposite to each other, as indicated by the bold line arrows in FIG. 5a. It's getting old. Furthermore, as shown in Figure 5c, the radial distribution of the vibration amplitude δ is
The amplitude near the nozzle 54 is large, and the piezoelectric vibrator 5
5 has a very small swing width. Therefore, the possibility of cavitation occurring due to the vibration of the flexural vibrator is greatest in the vicinity of the nozzle 54, and the kerosene in the vicinity of the nozzle 54 is injected from the nozzle 54 before the dissolved air becomes excessively bubbly. Even liquids containing a large amount of dissolved air, such as kerosene, can be stably injected and atomized without being affected by cavitation bubbles. Cavitation occurs near the piezoelectric vibrator 55 because the vibration phases of the nozzle 54 and the piezoelectric vibrator 55 are opposite to each other.
The flow of kerosene as shown by the thin arrows in Figure 5 a and b occurs and acts in the direction of suppressing the occurrence of cavitation (that is, the direction of suppressing depressurization), so that most of the dissolved air becomes bubbles due to cavitation in this area. Moreover, even if bubbles are generated in the vicinity of the nozzle 54, the bubbles are removed along the flow of kerosene in a different circumferential direction of the pressurizing chamber 46 and are discharged from the pipe 38. Therefore, by configuring the piezoelectric vibrator to vibrate in this vibration mode, stable operation of the piezoelectric vibrator is guaranteed.

FIG. 6a illustrates the operation when the nozzle 54 and the piezoelectric vibrator 55 flexurally vibrate in the same phase vibration mode, and the same reference numerals as in FIG. 3 correspond to the same components. Even when the nozzle 54 and the piezoelectric vibrator 55 vibrate in the same phase as shown by the arrows in FIG. 6a, the radial distribution of the amplitude δ is The vicinity is large, and the amplitude of the piezoelectric vibrator 55 is very small. However, when vibrating in such a vibration mode, as shown in FIG. This causes disturbance in the spraying state of atomized particles, making it impossible to maintain a stable atomization pattern.

FIGS. 7a to 7e explain the vibration modes in FIGS. 5 and 6 in more detail, and the same reference numerals as in FIG. 3 correspond to the vibration modes shown in FIGS.

In Fig. 7a, the flexural vibrating body composed of the piezoelectric vibrator 55 and the nozzle plate 52 is shown in Fig. 7b,
It can be divided into two parts as shown in c. The central nozzle plate 52' in FIG.
The periphery of the piezoelectric vibrator 55 is fixed at a fixing part 60 along the inner circumference of the piezoelectric vibrator 55 to perform flexural vibration, while the piezoelectric vibrator 55
It can be considered that the asymmetric bimorph vibrating body 61 consisting of the nozzle plate 52 and the nozzle plate 52 is fixed at the periphery by the fixing part 62 of the body 47 and flexibly vibrates. This is because the vibrating part 61 in figure b
This is because there is a significantly large difference in level between the vibration amplitude δ of the vibration amplitude δ and the vibration amplitude δ′ of the vibration portion 52′ shown in FIG.

The vibrating part 61 in figure b is the vibrating part 5 in figure c.
2' is an excitation source as a load, and it is important to match the resonance frequencies of these two vibrating bodies and match the mechanical impedances in order to achieve efficient atomization operation.

By the way, these two vibrating bodies 61, 52'
When expressed as a model by replacing the lumped masses m ₂ and m ₁ , it can be considered as a one-dimensional oscillating system as shown in Fig. 7d and e. That is, m ₁ corresponds to 52', and 1/2 m ₂ is the left and right vibration portion of 61. If a ₁ and a ₂ are vibration accelerations of m ₁ and m ₂ , respectively, then the vibration mode of Fig. 5, Fig. 7 e
The vibration mode in FIG. 6 corresponds to FIG. 7d.

Considering the forces F _S and F _S ' in the vibration direction generated on the fixed end 62 in Figure 7 d and e, respectively, F _S = m ₂ a ₂ + m ₁ a ₁ in Figure 7 d and F _S in Figure 7 e. ′=m ₂ a ₂ −m ₁ a ₁ , and it is clear that F _S ′<F _S. Depending on the quality of the mechanical impedance matching between m ₁ and m ₂ , F _S ′ becomes F _S It can be made significantly smaller than that. This is extremely important for simplifying the structure and stabilizing the operation.

In other words, since F _S ′ mentioned above is very small,
When operating in the secondary vibration mode shown in FIG. 5, the vibration performance required of the body 47 is extremely low compared to the case of the primary vibration mode shown in FIG. It will be fine if it is of a certain level.

In other words, the vibration energy of the flexural vibrator is extremely difficult to be transmitted to the body 47, and the mechanical impedance of the flexural vibrator as seen from the body 47 becomes high.

Therefore, even if the structure of the body 47 is simple, stable flexural vibration of the flexural vibrator can be guaranteed, and since the transmission of vibrational energy to the body 47 is small, as shown in Fig. 6a, Cavitation bubbles 59 are prevented from being generated throughout the pressurizing chamber 46, and stable atomization operation can be guaranteed with a simple structure.

Also, the fact that the mechanical impedance of the deflection vibrator is high when viewed from the body 47 means that the body 47
Since the mounting conditions have a very small influence on the deflection vibrator, it is possible to realize an atomization device that is extremely easy to handle.

In this way, the configuration in which the nozzle plate 52 and the piezoelectric vibrator 55 are energized in a second-order or higher-order vibration mode in which the vibration phases are opposite to each other allows the nozzle 54 and the piezoelectric vibrator 55 to be energized in the vicinity. It is possible to generate a liquid flow in the pressurizing chamber 46 that suppresses the generation of cavitation bubbles, and to increase the mechanical impedance of the deflection vibrating body when viewed from the body 47, so that even with a simple body structure, the body 47 itself It is possible to prevent problems such as cavitation bubbles occurring in the pressurized chamber due to vibration being transmitted to the pressurized chamber, or vibration conditions changing depending on the mounting conditions of the body. Can be stably atomized.

FIG. 8 is a sectional view showing another embodiment of the atomizing device of the present invention, and the same reference numerals as in FIG. 3 correspond to the same ones. In this embodiment, the nozzle plate 52 is not provided with a protrusion, so that the nozzle 54 generates a plurality of straight-advance droplet arrays.

FIG. 9 is a sectional view showing still another embodiment of the present invention, and the same reference numerals as in FIG. 3 are equivalent. In this embodiment, no exhaust pipe is provided and only one nozzle 54 is provided, which is capable of producing a single droplet train.

FIG. 10 is a sectional view showing yet another embodiment of the present invention, and the same reference numerals as in FIG. 3 are equivalent. In this embodiment, the piezoelectric vibrator 55 is provided only at the antinode of the flexural vibration, indicating that it is only necessary to use a vibration mode in which no vibration nodes occur on the piezoelectric vibrator 55. Moreover, the diameter of the pipe 36 is almost the same as the diameter of the pressurizing chamber 46,
This shows that the shape of the pressurizing chamber 46 essentially does not affect the present invention.

As described above, various embodiments can be taken without departing from the technical idea of the present invention.

Effects of the Invention As described above, according to the present invention, a pressurizing chamber is filled with liquid, and a flexible vibrating body consisting of a nozzle plate and an electric vibrator is attached to a body so as to face the pressurizing chamber. , the structure is such that the bending vibrator is energized to excite the nozzle in a secondary or higher-order vibration mode in which the phases of the vibrations of the nozzle and the electric vibrator are opposite to each other. It is simple and compact, therefore low-priced, and has excellent atomization, uniformity of particle size, stability of atomization pattern, and controllability of atomization operation despite extremely low power consumption. It is possible to provide an atomization device.

In particular, by using a configuration that energizes the flexible vibrator in a vibration mode in which the vibrations of the nozzle and the electric vibrator are in opposite phases to each other, the effects of cavitation can be minimized even with ordinary liquids containing a large amount of melt air. It is possible to provide an extremely versatile atomization device because it is able to atomize extremely stably without being affected, and is not affected by installation conditions and is easy to handle, and its industrial value is It is extremely large.

[Brief explanation of the drawing]

Figures 1 a, b, and c are cross-sectional views of a conventional atomizing device, Figure 2 is a cross-sectional view of a hot air fan to which an atomizing device according to an embodiment of the present invention is applied, and Figure 3 is a cross-sectional view of the same atomizing device. Detailed sectional view, Figures 4a, b, c, d, and e are drive voltage waveform diagrams of the electric vibrator according to the amount of atomization, and Figures 5a and b are flexural vibrations of the atomization device in Figure 3. FIG. 6(c) is a radial distribution diagram of the vibration amplitude of the same flexural vibrator; FIG. 6(a) is a sectional view explaining another vibration mode of the same flexural vibrator; FIG. The radial distribution diagram of the vibration amplitude of the flexural vibrator in the same vibration state, Figures 7a to 7e are cross sections for modeling, explaining, and comparing the vibration state of the flexural vibrating body in Figures 5 and 6. 8 is a sectional view of an atomizing device showing another embodiment of the present invention, FIG. 9 is a sectional view of an atomizing device showing another embodiment of the present invention,
FIG. 10 is a sectional view of an atomizing device showing another embodiment. 46...pressure chamber, 47...body, 52...
Nozzle plate, 53... Protrusion, 54... Nozzle, 5
5... Electric vibrator (piezoelectric vibrator), 56... Opening.

Claims (1)

[Scope of Claims] 1. A flexible vibrating body consisting of a nozzle plate having a nozzle and a plate-shaped electric vibrator, and a body having a pressurizing chamber, and the flexible vibrating body is arranged so as to face the pressurizing chamber. Attached to the body, the nozzle is vibrated by energizing the flexural vibrator in a secondary or higher order flexural vibration mode in which the vibrations of the nozzle and the electric vibrator are almost in opposite phases. Atomization device configured to do this. 2. The atomization device according to claim 1, wherein the electric vibrator is provided with an opening, and the bending vibrator is configured such that the nozzle faces the opening. 3 The electric vibrator is composed of a disc-shaped piezoelectric vibrator,
3. The atomization device according to claim 1, wherein the deflection vibrating body is a circular deflection vibrating body. 4. The atomization device according to claim 1, 2, or 3, wherein a nozzle plate is provided with a protrusion, and the protrusion is provided with a plurality of nozzles.