JPH10287127A - Vibration damping device of window glass for automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration damping device of window glass for automobile which can obtain a much higher damping action without bringing a weight increase. SOLUTION: A vibration damping device of window glass for automobile is composed by providing a piezoelectric-crystal element provided by closely contacting to the outer periphery of a window glass 27 for automobile; and a control means to control the distortion amount of the piezoelectric-crystal element; and an inner stress in the direction to constrain the distortion resulting from an elastic vibration generated to the window glass for automobile is made generating to the piezoelectric-crystal element. As a result, a force to suppress the deflection of the outer periphery of the window glass by controlling the voltage applied to the piezoelectric-crystal element can be generated to the piezoelectric-crystal element. Consequently, the aparant rigidity at the outer periphery of the window glass is increased, and the elastic vibration of the window glass can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration damping device for an automobile window glass.

[0002]

2. Description of the Related Art In-vehicle noise is promoted by vibrating sound generated from a driving system such as an engine or undercarriage resonating in a cavity in a vehicle space as a resonance space. In particular, a so-called membrane vibration in which a relatively large flat plate portion such as a roof, a floor, or a window glass elastically vibrates emits a muffled sound having a high sound pressure and causes a decrease in comfort in the vehicle.

[0003] In order to promote quietness in a vehicle cabin, it is effective to make the flat plate portion itself difficult to vibrate as described above.
In the case of metal plates, a method of increasing the rigidity by providing ribs or beads for reinforcement, or a method of increasing the transmission loss by heat-sealing an asphalt sheet or spraying and applying a viscoelastic resin material are generally adopted. ing.

[0004]

However, a transparent body such as a window glass has no effective vibration damping means other than increasing the thickness dimension to remove a resonance frequency from a frequency band that is annoying to humans. Is the actual situation. However,
Adjusting the natural frequency with the thickness dimension cannot be a fundamental vibration suppression measure, but also has the disadvantage of increasing the weight.

[0005] The present invention has been devised to solve such problems of the prior art, and its main objects are as follows.
An object of the present invention is to provide a vibration damping device for a window glass for an automobile, which can obtain a higher vibration damping action without increasing the weight.

[0006]

In order to achieve the above object, according to the present invention, a vibration damping device for a vehicle window glass is provided in close contact with the outer peripheral portion of a vehicle window glass 27. It has an element 2 and control means 4 for controlling the amount of distortion of the piezoelectric conversion element, and applies an internal stress to the piezoelectric conversion element in a direction to restrain the distortion caused by the elastic vibration generated in the window glass for an automobile. To be generated. According to this, by controlling the voltage applied to the piezoelectric conversion element by the control means, a force for suppressing the bending of the outer peripheral portion of the window glass can be generated in the piezoelectric conversion element. Therefore, the apparent rigidity of the outer peripheral portion of the window glass is increased, and the elastic vibration of the window glass is suppressed.

The piezoelectric transducers include PZT (zirconate titanate), PLZT (lanthanum zirconate titanate), and PMN (magnesium niobium lead oxide).
PVDF (polyvinylidene fluoride) and the like are used.

[0008]

Embodiments of the present invention will be described below in detail with reference to the embodiments shown in the accompanying drawings.

FIG. 1 shows a damping panel used in the present invention. The vibration damping panel 1 generates a voltage according to the strain and generates a strain according to the applied voltage. As shown in FIG. 2, a rectangular flat-plate-shaped piezoelectric conversion element made of PZT or the like is used. 2, a pair of copper electrodes 3 provided on both front and back surfaces of the piezoelectric conversion element 2, a control circuit 4 connected to the pair of copper electrodes 3,
It has an epoxy resin coating 5 integrated by thermocompression bonding so as to cover the copper electrode 3 and the control circuit 4. Further, a conductive sheet 6 containing Ni is provided between the piezoelectric transducer 2 and the copper electrode 3, and a polyimide film 7 is provided on both front and back surfaces of the cover 5.

The control circuit 4 is a resonance analog circuit having a frequency characteristic corresponding to the resonance frequency of the window glass. Specifically, as shown in FIG. A resistor R is connected in series, or a capacitor C is connected in parallel to the resistor R and the coil L connected in series as shown in FIG.

FIG. 5 shows the area around the rear windshield to which the present invention is applied. As shown in FIG. 6, the rear glass mounting portion of the rear windshield 21 is formed by bending an inner peripheral edge of an opening formed from the roof 22 to the rear pillar 23 toward a vehicle interior, and then further connecting the edge to the center of the opening. And has a flange portion 24 which is formed in a stepped manner by being bent toward. And this flange 2
The outer peripheral edge of the rear glass 27 is adhered to the inner peripheral edge of 4 with an adhesive 26 applied via a dam rubber 25. Further, a plurality of vibration damping panels 1 are sandwiched between the rear glass 27 and the flange portion 24 at a proper interval along the outer peripheral edge of the rear glass 27 so as to be in close contact with the outer peripheral edge of the rear glass 27. I have.

The gap between the outer peripheral edge of the rear glass 27 and the vehicle body window frame is closed by a molding member 28 that performs a sealing function.

Next, the operation principle of the device of the present invention will be described.

For example, when a three-node bending vibration as shown in FIG. 7 occurs in the rear glass 27, a strain (arrow A) in the extension direction is applied to one of the vibration damping panels 1 disposed between the nodes in the secondary vibration mode. And distortion in the compression direction (arrow B) occurs on the other side. Then, when the rear glass 27 starts to vibrate at the resonance frequency, the control circuit 4 having a frequency characteristic corresponding to the resonance frequency applies a force for suppressing the distortion of the piezoelectric conversion element 2, that is, the direction for suppressing the distortion of the rear glass 27. The piezoelectric conversion element 2 of each vibration damping panel 1
Voltage. Thereby, the apparent rigidity of the outer peripheral edge portion of the rear glass 27 is increased, and the bending deformation of the rear glass 27 is suppressed, and as a result, the elastic vibration of the rear glass 27 is suppressed.

In the above embodiment, the passive control by the analog circuit built in the vibration damping panel 1 has been described. As shown in FIG. 8, the vibration of the window glass G is detected by the acceleration sensor 11 and the acceleration is detected. The output of the sensor 11 is processed by the control circuit 12 to determine the vibration frequency and the vibration amplitude of the window glass G, and a voltage for generating a vibrating force in a direction to cancel the vibration of the window glass G is supplied from the battery 13 to the amplifier 14. It is also possible to use an active control in which the voltage is applied to the piezoelectric conversion element 2 via the control circuit. According to this, the frequency of the voltage applied to the piezoelectric conversion element 2 can be freely adjusted in accordance with the vibration frequency and the vibration amplitude of the window glass G, so that vibration can be suppressed over a wide range, and it is difficult with the conventional method. It is also possible to control the vibration in a low frequency region.

The vibration of the window glass is measured by the acceleration sensor 1
In addition to the detection in step 1, the piezoelectric conversion element 2 itself has a function of outputting a voltage corresponding to the amount of distortion, so that the applied voltage may be controlled so as to cancel the output.

The installation place of the damping panel 1 does not necessarily have to be sandwiched between the glass and the flange portion, and may be on the inner surface of the glass along the inner periphery of the window frame as long as it does not affect the field of view. In particular, in the range of black ceramic coating, the appearance is not affected at all. Although the above embodiment has been described on the rear side, it is needless to say that the embodiment can be similarly carried out on a front side or side mounting window.

[0018]

As described above, according to the present invention, the vibrating force generated by the piezoelectric transducer can cancel the elastic vibration generated in the window glass, so that the vibration response level of the resonance frequency can be reduced. Needless to say, since vibration can be suppressed over a wide frequency band, a great effect can be obtained in further reducing the noise in the vehicle. In particular, since it can be provided along the outer peripheral edge of the glass, the field of view does not need to be narrowed.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of a vibration damping panel according to the present invention.

FIG. 2 is a sectional view of the vibration damping panel shown in FIG.

FIG. 3 is a conceptual diagram showing a configuration example of a control circuit built in the damping panel shown in FIG.

FIG. 4 is a circuit diagram showing another configuration example of a control circuit built in the vibration damping panel shown in FIG. 1;

FIG. 5 is a perspective view showing the periphery of a rear windshield to which the present invention is applied.

FIG. 6 is a partially enlarged cross-sectional view along the line VI-VI of FIG. 6;

FIG. 7 is an explanatory view of the operation principle of the vibration damping panel.

FIG. 8 is a block diagram showing another control method of the vibration damping panel.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 damping panel 2 piezoelectric conversion element 3 copper electrode 4 control circuit 5 covering 6 conductive sheet 7 polyimide film 11 acceleration sensor 12 control circuit 13 battery 14 amplifier 21 rear windshield 22 roof 23 rear pillar 24 flange 25 dam rubber 26 adhesive 27 Rear glass 28 Molding member

Claims (1)

[Claims] A piezoelectric transducer disposed in close contact with an outer peripheral portion of a window glass for an automobile, and control means for controlling a distortion amount of the piezoelectric transducer, wherein elasticity generated in the window glass for the automobile is provided. A vibration damping device for a window glass for an automobile, wherein an internal stress in a direction for restraining distortion caused by vibration is generated in the piezoelectric conversion element.