JP2774188B2 - Frequency adjustment method of drip-proof ultrasonic transducer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for adjusting the frequency of a drip-proof ultrasonic vibrator having an ultrasonic vibrator for transmitting and receiving ultrasonic waves having a drip-proof structure.

[Prior Art] Conventionally, this type of drip-proof ultrasonic vibrator has a configuration as shown in FIG. A piezoelectric element 3 is attached to the inner bottom surface of a cylindrical vibration case 1 having a truncated conical cross section. 4
Is a felt material, which is bonded to the back surface of the piezoelectric element 3. A positive lead wire 5 is joined to the piezoelectric element 3. The inner side 1b of the tapered surface of the vibration case 1 is bonded to the vibration isolator 2 with an elastic adhesive. Negative lead wire 6
Is connected to the straight pipe portion 1c of the vibration case 1, and the positive lead wire 5 and the negative lead wire 6 are shielded wires 7
It is connected to the. 1a indicates a J-shaped folded portion of the vibration case 1, and 8 is a filler.

[Problems to be Solved by the Invention] By the way, the drip-proof ultrasonic vibrator having the above structure is manufactured when only the vibration case 1 is in a state or when it is completed as a drip-proof ultrasonic vibrator. There are variations in time and errors, so that it may be necessary to adjust to the target frequency. This type of frequency adjustment is performed by changing the plate thickness of the vibration surface 1d of the vibration case 1, and the frequency can be lowered by reducing the plate thickness. However, in the case of a drip-proof ultrasonic transducer used outdoors, such as that used for vehicles, the outer surface of the vibration case is painted for rust prevention and corrosion prevention.
If the thickness of the vibrating surface is cut off from the outside for frequency adjustment, there is a disadvantage that these effects are lost.

The present invention has been made in view of such a point,
An object of the present invention is to provide a method of adjusting the frequency of a drip-proof ultrasonic vibrator capable of adjusting the frequency by extremely simple processing.

[Means for Solving the Problems] In the present invention, in order to solve the above problems, as shown in FIG. 1, a cylindrical vibrating case 1 having a truncated conical cross section and one end opened. Attach the piezoelectric element 3 to the inside of the bottom,
A drip-proof type in which the vibration-proof material 2 is inserted so as to contact the inner side 1b of the tapered surface of the cylindrical vibration case 1 and the peripheral edge of the opening end of the vibration case 1 is folded inward in a J-shape to press the vibration-proof material 2 In the ultrasonic vibrator, the frequency is adjusted by adjusting the mechanical Q value by applying pressure to the vibration isolator 2 of the J-shaped folded portion 1a.

Further, the frequency may be adjusted by changing the area of the contact portion between the vibration isolator 2 and the inner side 1b of the tapered surface of the vibration case 1.

[Operation] In the present invention, the mechanical Q value is adjusted as shown in FIG. 2 by changing the pressing force of the J-shaped folded portion 1a of the vibration case 1 on the vibration isolator 2 or As shown in FIG. 3, the frequency can be adjusted by changing the area of the contact portion between the vibration isolator 2 and the inside 1b of the tapered surface of the vibration case 1.

Embodiment FIG. 1 shows the structure of a drip-proof ultrasonic transducer to which the frequency adjustment method of the present invention is applied. This is the same as the structure shown in FIG. 4, but the shape of the vibration isolator 2 is slightly different.
The frequency can be adjusted by changing the pressure at the adjustment point A or by changing the contact length 1 at the adjustment point B. The pressure applied to the vibration isolator 2 by the J-shaped folded portion 1a is
The smaller the height L in FIG. 1, the larger the height, and the larger the height L, the smaller the pressing force. As the height L increases, as shown in FIG. 2, the mechanical Q value decreases, and the relationship between the mechanical Q value and the frequency (resonance frequency) is as shown in FIG. In addition, the mechanical Q value can be controlled by changing the pressing force, and the frequency can be adjusted. When the length 1 of the bonding portion between the tapered inner surface 1b of the vibration case 1 and the vibration isolator 2 is changed, that is, when the contact area is changed, as shown in FIG. ) Changes.

As described above, according to the present embodiment, the change in the length l of the adhesive portion between the inner side 1b of the tapered surface of the vibration case 1 and the vibration isolator 2
Since the mechanical Q value can be controlled by changing the frequency by changing the pressing force from the character folded portion 1a, that is, the change in the height L, the frequency can be adjusted.

[Effects of the Invention] As described above, according to the present invention, in the drip-proof ultrasonic vibrator, the pressing force of the J-shaped folded portion on the peripheral edge of the opening end of the vibration case is changed, or The frequency of the vibrator can be adjusted by changing the contact area between the inner side of the tapered surface of the vibrator and the vibration isolator inside the vibrating case, and the structure of the conventional drip-proof ultrasonic vibrator can be almost changed. Frequency adjustment can be performed very easily, and it is not necessary to cut off the vibrating surface in order to reduce the thickness of the vibrating surface as in the conventional case, eliminating the risk of rust and corrosion. This has the effect.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing the structure of a drip-proof ultrasonic transducer to which the frequency adjustment method of the present invention is applied, FIG. 2 is an explanatory view showing a change in mechanical Q value due to a pressing force, and FIG. FIG. 4 is an explanatory view showing a change in resonance frequency due to a mechanical Q value, and FIG. 4 is a sectional view of a conventional example. 1 is a vibration case, 1a is a J-shaped folded portion, 1b is the inside of the tapered surface, 2 is an anti-vibration material, 3 is a piezoelectric element, 4 is a felt material, 5,
6 is a lead wire, 7 is a shield wire, and 8 is a filler.

Claims (2)

(57) [Claims] 1. A piezoelectric element is adhered to the inside of the bottom surface of a cylindrical vibration case having a truncated conical cross section and one end opened, and a vibration-proof material is inserted so as to contact the inside of the tapered surface of the cylindrical vibration case. ,
A drip-proof ultrasonic vibrator for pressurizing a vibration-proof material by folding a peripheral edge of an opening end of a vibration case inward in a J-shape.
A frequency adjustment method for a drip-proof ultrasonic vibrator, wherein a frequency is adjusted by adjusting a mechanical Q value by a pressing force applied to a vibration-proof material in a character-shaped folded portion. 2. A piezoelectric element is adhered to the inside of the bottom surface of a cylindrical vibration case having a truncated conical cross section and one end opened, and a vibration isolator is inserted so as to contact the inside of the tapered surface of the cylindrical vibration case. ,
In a drip-proof ultrasonic vibrator that presses the vibration-proof material by folding the periphery of the opening end of the vibration case inward in a J-shape, the area of the contact part between the vibration-proof material and the inside of the tapered surface of the vibration case is changed. A frequency adjustment method for a drip-proof ultrasonic vibrator, wherein the frequency is adjusted by adjusting the frequency.