JPH045463A - Fuel atomizer device - Google Patents

Abstract

PURPOSE:To effectively atomize even a fuel having a large flow rate by forming a horn for amplifying the vibration from an oscillator in such a manner that it has a hollow sectional form and its area is changed decreasingly toward the oscillating surface to increase the outer diameter of the oscillating surface. CONSTITUTION:When a high frequency oscillation pulse (drive pulse) conforming to the resonance frequency of an ultrasonic oscillator 2 is inputted to a piezoelectric element 1 from a control unit 6 during the operation of an engine, the ultrasonic oscillator 2 causes a vertical vibration of half wave length mode, which vibration is extended at an extension ration determined depending on the size of the input end surface and output end surface of a horn 3 to vigorously vibrate an oscillating surface 4. On the other hand, a fuel is then jetted toward the oscillating surface 4 from an injector 5, whereby a fuel mist 7 is uniformly extended to each part of the oscillating surface 4, and the surface of the fuel mist 7 is waved by the vibration of the oscillating surface 4 and atomized. This horn 3 allows an increase in outer diameter of the oscillating surface 4 as its outer diameter is never reduced, and also has a small weight because of its hollow form, and even a fuel having a large flow rate can be effectively atomized.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a fuel atomization device for engines such as automobiles, and more particularly to a fuel atomization device that atomizes fuel using an ultrasonic vibrator. .

(Prior Art) In recent years, requirements for automobile engines have become more sophisticated, and issues such as low fuel consumption, reduction of harmful exhaust gases, and drivability are all required to be achieved at a high level. Therefore, in an injector-type engine that injects fuel, it is important to take measures to atomize the fuel.

A conventional fuel atomization device using an ultrasonic vibrator for atomizing fuel is, for example, disclosed in Japanese Patent Application Laid-Open No. 64-5696.
Publication No. 2, JP-A-1-104368, and Utility Model Application No. 61
There are those described in Publication No.-36167 and the like. All of these devices use a step-like horn attached to a vibrator using a piezoelectric element to magnify the vibration, and the tip of the horn has a vibrating surface with a diameter larger than the outside diameter of the horn. Ringed fuel (metered internally in the former device, externally in the latter device) is supplied to this vibrating surface to atomize it. Note that the shape of the vibrating surface is generally curved toward the inside in the opposite direction to the vibrator, so that the atomized fuel is concentrated in one direction.

(Problem to be Solved by the Invention) However, in such a conventional fuel atomization device, the tip of the small diameter part of the step-type horn has a vibration surface with a larger diameter. In order to effectively atomize the fuel, it is necessary to make the vibration surface large, but if it is made too large, the weight will increase and the horn vibration will no longer vibrate the fuel, making it impossible to atomize it. Therefore, there is a problem in that the amount of fuel that can be atomized is limited to a small amount.

(Object of the Invention) Therefore, an object of the present invention is to provide a fuel atomization device that can increase the outer diameter of a vibrating surface and can effectively atomize even a large flow of fuel.

(Means for Solving the Problems) In order to achieve the above object, the fuel atomization device according to the present invention includes a vibrator that generates ultrasonic waves, a horn that amplifies the vibrations from the vibrator, and a tip of the horn. with a vibrating surface,
In a fuel atomization device that supplies fuel from a fuel supply device to the vibrating surface to atomize the fuel, the horn has a hollow cross-sectional shape and an area that is small (varies) in the direction of the vibrating surface. It is formed.

(Function) In the present invention, vibrations from a vibrator that generates ultrasonic waves are amplified by the horn and transmitted to the vibrating surface at the tip of the horn.

At this time, when the fuel spray is supplied to the vibrating surface, the fuel spray is atomized by the vibration of the vibrating surface.

In this case, since the horn has a hollow cross-sectional shape and its area changes small in the direction of the vibration surface, the outer diameter of the vibration surface can be increased, and the weight of the horn is also small. , even a large flow rate of fuel can be effectively atomized.

(Example) Hereinafter, the present invention will be explained based on the drawings.

FIG. 1.2 is a diagram showing an embodiment of the fuel atomization device according to the present invention.

First, the configuration will be explained. Figure 1 is a configuration diagram of this device. In this figure, ■ is a piezoelectric element, 2 is a Langevin type ultrasonic transducer using piezoelectric element 1, 3 is a horn, and 4 is a
is the vibration surface of the horn, 5 is the injector (fuel supply device)
, 6 is a control unit. The Langevin type ultrasonic vibrator 2 vibrates in the range of several kHz to several tens of kHz, and has the characteristic that it can atomize a large amount of fuel per unit time, compared to, for example, an immersion type ultrasonic vibrator. ing. A vibration pulse (driving pulse) matching the resonant frequency of the Langevin-type ultrasonic transducer 2 is inputted to the piezoelectric element 1 from the control unit 6, and the ultrasonic transducer 2
generates a predetermined ultrasonic vibration based on this vibration pulse. One end surface 2A of the Langevin type ultrasonic vibrator 2 is connected to a horn 3, and vibrations of the ultrasonic vibrator 2 are transmitted to the horn 3 from this one end surface 2A. The horn 3 magnifies the transmitted vibration at a magnification rate determined by a change in its cross-sectional area. Further, the horn 3 has a cylindrical shape and is hollow inside, with a hollow recess 3B formed therein. Therefore, the horn 3 is formed so that its cross-sectional shape is hollow, and the area of the member changes small in the direction of the vibration surface 4.

Furthermore, the outer diameter of the horn 3 is the connection surface 3 with the ultrasonic transducer 2.
It cannot be smaller than the outer diameter of A. On the other hand, a vibration surface 4 is fixed to the other connection surface of the horn 3. Vibration surface 4
An injector 5 is arranged outside the injector 5.
measures the amount of fuel based on the fuel injection pulse from the control unit 6 and supplies fuel spray 7 toward the vibrating surface 4. The fuel spray 7 is spread uniformly over each part of the vibrating surface 4.

Next, the effect will be explained.

When the control unit 6 inputs a high-frequency vibration pulse (driving pulse) matching the resonance frequency of the ultrasonic vibrator 2 to the piezoelectric element 1 while the engine is running, the ultrasonic vibrator 2 operates vertically in half-wavelength mode. cause vibration. This longitudinal vibration is magnified by the horn 3, and the magnification rate is determined by the size of the input end face and the output end face of the horn 3, and the larger the ratio, the greater the magnification rate. Further, it is necessary to determine the length of the horn 3 so that it vibrates in the half-wavelength mode.

Here, between the resonant frequency f and the wavelength λ, there is r · λ−
Since there is a relationship C, the length of the horn 3 is determined from this second. However, C is the speed of sound, which is determined by the material of the horn 3. The vibration in the horn 3 is caused by the ultrasonic vibrator 2
On the opposite side (that is, the vibration surface 4 side), the amplitude is several μ
m - reaches as many as 10 μm, causing the vibrating surface 4 to vibrate violently. On the other hand, at this time, a fuel injection pulse corresponding to the required amount of fuel is inputted to the injector 5 from the control unit 6, and fuel is injected from the injector 5 toward the vibration surface 4 only during that time. The fuel spray 7 from the injector 5 spreads uniformly to each part of the vibrating surface 4, and the vibration of the vibrating surface 4 causes the surface of the fuel spray 7 to ripple and become atomized. At this time, if the vibrating surface 4 is small or the amount of fuel spray 7 is large, the weight of the fuel per unit area becomes large, the vibration of the vibrating surface 4 becomes small, and the fuel cannot be atomized.

On the other hand, in this embodiment, the outer diameter of the horn 3 is small, so the outer diameter of the vibrating surface 4 can also be made large, and since the horn 3 is hollow, its weight is small, and therefore a large flow rate is achieved. can be effectively atomized.

In other words, in order to effectively atomize the fuel, the vibration surface 4
It is necessary to increase the value, but if it is made too large, the weight will increase and the vibration of the horn 3 will no longer vibrate the fuel, making it impossible to atomize it, and as a result, the amount of fuel that can be atomized will be limited to a small amount. However, in this embodiment, the outer diameter of the vibrating surface 4 is large, the horn 3 is hollow, and the weight is small, so even a large flow rate of fuel can be effectively atomized.

Note that the atomization level of the fuel can be changed by changing the resonant frequency of the ultrasonic vibrator 2 as necessary. The relationship between frequency and atomization level is shown in FIG. In the figure, the spray particle diameter d is given by the following equation.

However, k is a proportionality constant, and is set to, for example, =4 based on water atomization data. σ is the surface tension, for example o = 0.0
025 kg/m, ρ is specific gravity, for example ρ-75
0 kg/m3. In an internal combustion engine, for example, the number 1
It has been confirmed that atomizing fuel to 0tjm improves mixing with air, stabilizes combustion, and significantly improves emissions and fuel efficiency.

Next, FIG. 3 is a diagram showing another embodiment of the present invention. In this embodiment, the horn is provided in two stages to further expand the amplitude, and a valve is provided inside the first stage horn to fuel the fuel. It has a metering function.

That is, in FIG. 3, one end surface 2 of the ultrasonic transducer 2
A is connected to the first horn 11, and one end surface 11A of the first horn 11 is larger than the outer diameter of the ultrasonic transducer 2. The first horn 11 has a cylindrical shape, and the other end has a smaller outer diameter, and as shown in detail in FIG. 13 is housed therein, and a fuel passage 14 is formed in the center. Further, the valve 12 contacts the seat portion 15 forming a part of the fuel passage 14 under the biasing force of the spring 13, and can close the fuel passage 14.
Lifts using ultrasonic vibration. Note that the valve 12 has a fuel metering function. The first horn 11 is connected to a second horn 16, and the second horn 16
has a cylindrical shape and is hollow inside, with a hollow recess 16B formed therein as in the previous embodiment, and a vibration surface F is fixed to the other connecting surface.

Further, a passage is formed inside the second horn 16 to allow the fuel from the fuel passage 14 of the first horn 11 to pass therethrough (path shown). The high frequency pulse input from the control unit node 6 to the piezoelectric element 1 is an intermittent pulse as shown in FIG.
), the valve 12 lifts.

In the above configuration, in this embodiment, when intermittent pulses as shown in FIG. 5 are input to the piezoelectric element 1, ultrasonic vibration is generated in the ultrasonic vibrator 2, and Due to the two-stage structure of the horn 16, the amplitude of the ultrasonic vibration is further expanded, and the valve 12 is lifted by the ultrasonic vibration to perform fuel metering. Here, the principle by which the valve 12 lifts is as follows. That is, when the first horn 11 generates ultrasonic vibration, the valve 12 is struck through the seat portion 15, and the valve 12 vibrates at the natural frequency of the system of the valve 12 and the spring 13.
It is something that lifts. The fuel metered by the first horn 11 passes through the fuel passage 14 and reaches the vibration surface 17, where it is atomized. Therefore, in this embodiment, the same effects as in the previous embodiment can be obtained, but there is an advantage in that fuel metering and atomization can be performed at the same time.

(Effects) According to the present invention, the cross-sectional shape of the horn is hollow and the area thereof changes small in the direction of the vibration surface, so the outer diameter of the vibration surface can be increased and the weight of the horn can be reduced. It can be made small, and even a large flow rate of fuel can be effectively atomized.

[Brief explanation of drawings]

Fig. 1.2 is a diagram showing an embodiment of the fuel atomization device according to the present invention, Fig. 1 is its configuration diagram, Fig. 2 is a diagram showing the relationship between its resonance frequency and atomization level, 3 to 5 are diagrams showing other embodiments of the fuel atomization device according to the present invention, in which FIG. 3 is a configuration diagram thereof, FIG. 4 is an enlarged view of section A in FIG. 3, and FIG. is a diagram showing high frequency pulses supplied to the piezoelectric element. 1...Piezoelectric element, 2...Langevin type ultrasonic vibrator, 3...
... Horn, 3B, 16B ... Hollow recess, 4 ... Vibration surface, 5 ... Injector (fuel supply device), 6 ...
... Control unit, 7 ... Fuel spray, 11 ... First horn, 12 ... Valve, 13 ... Spring, 14 ... ... Fuel passage, 15 ... Seat portion, 16 ... Second horn, 17 ... Vibration surface.

Claims (1)

[Claims] It is equipped with a vibrator that generates ultrasonic waves and a horn that amplifies the vibrations from the vibrator, has a vibrating surface at the tip of the horn, and supplies fuel to the vibrating surface from a fuel supply device to atomize the fuel. In the fuel atomization device, the horn is
A fuel atomization device characterized in that the cross-sectional shape is hollow and the area thereof changes small in the direction of the vibration plane.