JPH0118785B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a liquid atomization device that atomizes liquid fuel such as kerosene or light oil, water, medicinal solution, recording liquid, etc. using an electric vibrator. .

Conventional Structures and Their Problems Various types of liquid atomization devices have been proposed in the past, and many of them utilize the vibration phenomenon of electric vibrators.

Among the electric vibrators, the method of adjusting the spray amount in an ultrasonic atomization device using a piezoelectric vibrator is to drive the piezoelectric vibrator to oscillate near its mechanical resonance point, and to apply and stop the drive signal. There are things that change the ratio of FIG. 1 shows the state of this duty control. a shows the time change of the drive waveform in which the oscillation signal is applied and stopped at a predetermined cycle. During the above-mentioned stop time, no drive signal is applied at all, and after a predetermined period, a drive signal is applied in a steady state, that is, at a level at which actual atomization occurs. b is a diagram showing the amplitude change of the piezoelectric vibrator corresponding to the drive waveform of a above, and it can be seen that the amplitude gradually increases after the steady state drive vibration level is applied. c shows the time characteristic of the spray amount during the duty control described above.

In this manner, it can be seen that in the conventional duty control, the mechanical amplitude from the stopped state does not follow when the signal application starts, as shown by b, and the normal state is reached with a predetermined time constant. That is, at the beginning of signal application, not all of the applied energy contributes to mechanical vibration, but even if a large amount of energy is applied, it results in heat loss. Therefore, not only the efficiency of electrical to mechanical conversion was lowered, but also the mechanical strain on the piezoelectric vibrator joints was large, and problems remained in terms of service life. Furthermore, as can be seen in FIG. 1c, the envelope of the spray amount also gradually increases at the start of signal application. That is, the period until a steady state is reached is very long compared to the envelope of the drive waveform, and when adjusting the spray amount by duty control, it is difficult to correspond to the time ratio, making it troublesome to regulate the amount.

Purpose of the invention The present invention solves such conventional problems,
Even when adjusting the amount of atomization by duty control, the purpose is to reduce the heat loss of drive energy, reduce the strain on the joint of the piezoelectric vibrator, and obtain a sufficient amount of atomization with smooth vibration.

Structure of the Invention In order to achieve this object, the present invention includes a body provided with a pressurized chamber filled with liquid, a supply section for supplying liquid to the pressurized chamber, and a body facing the pressurized chamber. an atomizer comprising a nozzle part having a nozzle provided in the nozzle, an electric vibrator that energizes the nozzle part to vibrate the nozzle, and an oscillation drive that drives the electric vibrator at a predetermined frequency. and a duty control section that controls the drive signal level to the electric vibrator based on a time ratio.

With this configuration, conventionally, the signal level was zero during the stop time of the drive signal, but during the duty control period corresponding to the stop time, a predetermined small signal that does not contribute to the actual spraying is applied at a level. It has an effect.

DESCRIPTION OF EMBODIMENTS An atomizer which is an embodiment of the present invention will be described with reference to FIG. A body 2 including a pressurized chamber 1 filled with liquid is fixed to a mounting plate 4 with screws 3. The liquid enters the pressurizing chamber 1 through the supply pipe 5, and during the atomization operation, the gas discharge pipe 6 is filled halfway. Reference numeral 7 denotes a nozzle portion facing one side of the pressurizing chamber 1, and its outer periphery is joined to the body 2. A spherical protrusion 8 having a fine hole for ejecting droplets is formed in the center of the nozzle portion 7 . Furthermore, an annular electric vibrator, here a piezoelectric element 9, is attached to the nozzle portion 7. This piezoelectric element 9 is a piezoelectric ceramic polarized in the thickness direction, and has electrodes on the surface to be joined to the nozzle and on the opposite surface. Reference numeral 10 denotes a lead wire for transmitting a drive signal to the piezoelectric element 9, one of which is soldered to one electrode surface of the piezoelectric element 9, and the other is connected to the body 2 with a screw 11. When the mechanical vibration of the piezoelectric element 9 is excited by the drive signal, the nozzle part 7 is also energized and vibrates, so that the liquid in the pressurizing chamber 1 is discharged as atomized particles 12 as a result.

Incidentally, the liquid supplied to the pressurizing chamber 1 may be filled halfway into the gas discharge pipe 6 in the atomizer installation configuration, but as an alternative, the liquid supplied to the pressurizing chamber 1 may be and the exhaust pipe 6 is empty, and before entering the droplet ejection sequence, for example, the exhaust pipe 6 is empty.
Negative pressure may be applied through the pressure chamber 1 to fill the pressurized chamber 1 with liquid, and at the same time, the exhaust pipe 6 may be pulled up halfway. According to the latter means, impurities in the liquid solidify in the nozzle hole, and the problem that droplets cannot be ejected does not occur.

FIG. 3 shows a block diagram of the atomization device of the present invention, in which numeral 9 denotes a piezoelectric vibrator whose mechanical vibration is excited by a signal from an oscillation drive unit 13. The configuration of the oscillation drive section may be a separately excited type having an oscillator, or a self-excited type using the electrical characteristics of the piezoelectric vibrator 9. The duty control section 14 includes a vibration energy control section 15 that sends a control signal to the oscillation drive section in order to vary the drive signal of the oscillation drive section, that is, the amount of vibration energy applied to the piezoelectric vibrator, and a vibration energy control section 15 that sends a control signal to the oscillation drive section in order to vary the drive signal of the oscillation drive section, that is, the amount of vibration energy sent to the piezoelectric vibrator. Timer section 1 that controls time
It consists of 6.

FIG. 4 shows the driving state with the above configuration. a
is a drive waveform in which a predetermined drive signal level is applied at t=t ₀ and vibration energy necessary for actual spraying is given until t=t ₁ . The period from t=t ₁ to t=t ₂ is the stop time in the conventional example, and in the present invention, a predetermined level of vibration energy that does not contribute to actual spraying is applied. The level that does not contribute to spraying refers to the vibrational energy applied to the piezoelectric vibrator at a level that does not break the surface tension of the liquid in the nozzle spray hole. b shows the amplitude change of the piezoelectric vibrator with respect to the drive waveform in a. In comparison, b in FIG. 1 shows a very rapid rise from t=t ₀ to reaching a steady state. In addition, since the mechanical vibration of the piezoelectric vibrator is excited even during small signal operation, the amplitude rises and rises smoothly even immediately after applying the large signal necessary for spraying.
Heat loss does not occur as much as before. That is, the conversion efficiency becomes higher. Further, c shows an envelope curve for the change in spray amount over time, and it can be seen that the following characteristic of the drive waveform is better than that shown in FIG. 1c.

FIG. 5 shows another embodiment of the present invention, in which a driving waveform, b amplitude, and c spray amount are all expressed by envelopes. As can be seen in diagram a, the conventional stop time t=t ₁ to t=t ₂ is excited with a small drive signal whose level is changed at t=t ₃ .
The reason why the signal level from t= _t1 to t= _t3 is made smaller in this way is to make the fall of the amplitude of the piezoelectric vibrator faster and to clarify the break in the spray in duty control. and,
There is no spraying from t= _t3 to t= _t2 , but from _t1 <t
Apply a drive signal larger than the time < t ₃ and t =
This further accelerates the increase in mechanical vibration from t ₂ . With this configuration, the followability of the spray amount to the drive waveform is further improved as shown by c.

Incidentally, although the small signal level is set in two stages in FIG. 5, the same effect can be obtained even if the level is changed continuously instead of in a stepwise manner.

Effects of the Invention As described above, according to the atomization device of the present invention, the following effects can be obtained.

In duty control, by applying small-signal drive energy at a level that does not actually spray during the conventional stop period, the mechanical amplitude of the piezoelectric vibrator remains in a steady state after applying the drive energy necessary for spraying. The time it takes to reach is shortened.
That is, it has the effect of reducing loss of electrical vibration energy as heat loss, and at the same time, reducing mechanical strain at the joints of the piezoelectric vibrators. Furthermore, since the response of the actual spray amount becomes faster, the spray amount can be easily and reliably adjusted by controlling the time ratio.

[Brief explanation of drawings]

Figures 1a, d, and c are diagrams showing time changes in drive waveform, amplitude, and spray amount by conventional duty control means, respectively; Figure 2 is a sectional view of an atomizer showing an embodiment of the present invention; Figure 3 is a block diagram of the atomization device, Figure 4 is a diagram showing the drive waveform, vibration, and time changes in the amount of spray by the duty control means.
The figure is a diagram showing temporal changes in drive waveform, amplitude, and spray amount according to another embodiment of the duty control means of the present invention. DESCRIPTION OF SYMBOLS 1... Pressurization chamber, 2... Body, 5... Supply part, 7... Nozzle part, 9... Electric vibrator, 13
...Oscillation drive unit, 14...Duty control unit.

Claims (1)

[Claims] 1. A body equipped with a pressurized chamber filled with liquid;
a supply unit for supplying liquid to the pressurizing chamber; a nozzle unit having a nozzle facing the pressurizing chamber; and an electric vibrator that biases the nozzle unit and vibrates the nozzle. an oscillation drive unit that drives the electric vibrator at a predetermined frequency; and a duty control unit that controls the level of the drive signal to the electric vibrator in terms of time. conversion device. 2. Claim 1, comprising the duty control section that controls the ratio between the time for applying a predetermined signal level necessary for atomization and the time for applying a predetermined small signal level that does not atomize. Atomization device. 3. The atomization device according to claim 2, comprising a duty control section having a plurality of predetermined small signal levels at which no atomization occurs.