JPH0324343A - Vibration isolator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vibration isolator, and more particularly to a vibration isolator that suppresses mechanical vibrations generated in a mechanical member 12.

[Prior art] Conventional vibration isolators include devices that suppress mechanical vibrations by absorbing vibration energy using vibration isolating rubber, and devices that analyze the amplitude of mechanical vibrations. 2. Description of the Related Art There is a device that suppresses mechanical vibration by externally applying vibration having a phase opposite to that of the mechanical vibration to a mechanical member.

[Problems to be Solved by the Invention] However, there is a problem in that the above-mentioned structure cannot suppress mechanical vibrations generated in mechanical members in some cases.For example, in the former device using anti-vibration rubber, However, there is a problem in that it is not possible to suppress vibrations of a specific frequency, such as vibrations with a small frequency.In the latter case, in devices that apply vibrations from the outside, it is difficult to synchronize with the phase of the vibrations. In addition, this device requires an actuator that applies external vibration, a sensor that detects vibration, and high-speed calculation processing. There were problems in that the equipment became complex and sophisticated, such as the need to use a control circuit, and the resulting larger equipment required a relatively large space for installation, which placed restrictions on where it could be applied. The purpose of the vibration isolating device of the present invention is to solve the above problems and reliably suppress mechanical vibrations of mechanical members.

The configuration of the present invention that achieves this objective will be described below.

[Means for Solving the Problems] A vibration isolator of the present invention (a vibration isolator for suppressing mechanical vibrations generated by a mechanical member) includes a vibration isolator that is attached to the mechanical member, and a vibration isolator that suppresses mechanical vibrations generated by a mechanical member. An electromechanical conversion element that performs conversion, and an impedance element connected to the electromechanical conversion element and forming a closed circuit together with the electromechanical conversion element, the reactance component of the electromechanical conversion element and the impedance element forming a parallel circuit. The anti-resonance frequency of the circuit is made to substantially match the frequency of mechanical vibration of the mechanical member.

[Function] The vibration isolator of the present invention having the above configuration (upper) The electromechanical transducer attached to the mechanical member deforms with the mechanical vibration of the mechanical member, and generates an electrical signal of the same frequency as the mechanical vibration. When trying to generate an output, it behaves as follows.The parallel circuit constituted by the reactance component of the electromechanical transducer and the impedance element has an anti-resonance frequency approximately equal to the frequency of the mechanical vibration that the mechanical member is trying to suppress. Because they match, no current flows to the output end of the electromechanical transducer.The amount of deformation of the electromechanical transducer is proportional to the magnitude of the current at the output end, but as a result of this, no current flows to the output end. , deformation of the electromechanical transducer is prohibited, and mechanical vibrations of the mechanical members are suppressed.

[Examples] In order to further clarify the configuration and operation of the present invention described above, preferred embodiments of the vibration isolating device of the present invention will be described below.

(First Embodiment) FIG. 1 is a block diagram of a vibration isolator as a first embodiment of the present invention.

This vibration isolator is designed to suppress vibrations of a mechanical member M having electrical conductivity. ti piezoelectric element 1 adhered to mechanical member M, upper surface 1a of piezoelectric element 1 and yj. It consists of a variable coil 3 connected to the surface Ma of the mechanical member M.

The piezoelectric element 1 is made of zircon-lead titanate (PZT) or the like, and has electrodes 5 and 7 on its upper surface 1a and lower surface 1b. The electrode 5 on the upper surface 1a is directly connected to the variable coil 3, while the electrode 7 on the lower surface 1b is electrically connected to the mechanical member M to establish electrical continuity with the variable coil 3 via the mechanical member M. ing.

Variable coil method 3 This is a coil equipped with a variable mechanism that changes its inductance by adjusting the insertion and removal of the core.

FIG. 2 is a circuit diagram showing an electrical equivalent circuit of this vibration isolator. It is represented by a piezoelectric element 1 (mechanical compliance 9, force coefficient 11 and capacitance) 3. The anti-resonance frequency fa of the parallel circuit 14 constituted by the capacitance 13 and the coil 3 is given by the following equation.

Here, is the inductance of the variable coil 3, and C is the capacitance 13.

However, in the variable coil 3, the energy accumulated by its inductance component is greater than the energy consumed by its resistance component during one cycle.

In the vibration isolating device of this embodiment configured in this way, the piezoelectric element 1 receives the vibration of the mechanical member M and generates a voltage output having the same frequency as the FII mechanical vibration of the mechanical member M. Piezoelectric element 1
The parallel circuit 14 constituted by the capacitance 13 and the externally attached variable coil 3 has an anti-resonance frequency matched to the frequency of mechanical vibration of the mechanical member M, so that the current flows to the capacitance 13. The current is a large current whose phase is 90 degrees ahead of the change in voltage output with a force coefficient of 11. On the other hand, the current flowing through the variable coil 3 is a large current whose phase is delayed by 90 degrees with respect to the change in voltage output with a force coefficient of 11. This results in a large current. Since energy is only exchanged between these two elements, no current flows at the force coefficient 1112. That is, even if the force coefficient 11 generates a voltage output due to mechanical vibration, no current flows, so the mechanical torsion amplitude cannot be converted into a current output. In other words, {L At this time, the piezoelectric element 1 is prohibited from deforming, and the mechanical vibration of the mechanical member M is suppressed.

Experimental results regarding the vibration isolator of the first embodiment are shown below. FIG. 3 is a perspective view of the experimental apparatus.

A rectangular brass member is used as the mechanical member M, and its dimensions are length l = 60 [mm] and width W1 = 20 [mm].
+T1′n], thickness T 1 = 1 6 [ITvT+
]. 2 parallel to the end of this mechanical member M
Piezoelectric elements 15 and 17 that excite vibration are glued to the surface.
Dimensions (length L) of this piezoelectric element 15.17 for vibration excitation
2=23 [mm], width W2=13 [rlTrllll. Thickness T2=1 [cm]. Piezoelectric element 15 for vibration excitation
．． An AC high voltage generation circuit is connected to 17, and the mechanical member M
Two piezoelectric elements 19 and 21 as vibration isolators are attached to the other end of the mechanical member M constructed in this manner. Vibration isolation piezoelectric element 1 glued on the same two sides as excitation piezoelectric element 15 and 17
9.21 dimensions are length L3 = 25 [rm+], width W 3
= 6 [rnn], thickness T3-2 [ITm]. The bottom surface of the piezoelectric element 19.21 for vibration isolation is tl! ts member M
I: An experiment in which a variable coil 23.25 was connected electrically and between its upper surface and the surface of the machine member M. While gradually changing the inductance of the variable coil 23.25 of the vibration isolator, FIG. 3 is a graph showing the results of an experiment conducted by measuring the amplitude of mechanical vibration of member M. The horizontal axis represents the inductance of the variable coil 23.25, and the vertical axis represents the vibration excitation piezoelectric element 15.
Q per voltage input to 17! The amplitude E of the mechanical vibration actually generated in the mechanical member M is shown. In the figure, solid line A indicates the case where vibration isolation was performed using the vibration isolator, and solid line B shows the case where vibration isolation was not performed. From the solid line A, it can be seen that the amplitude of the vibration generated per input voltage in the mechanical member M is minimum when the inductance of the variable coil 23.25 is in the range of 17 m to 20 ml. The reason why the solid line A is not drawn in the range where the inductance is around 19 [m] is because the amplitude has become extremely small and cannot be measured. That is, the inductance of the variable coil 23.25 is 19 [m}
I] In the vicinity, the parallel circuit constituted by the capacitance of the vibration-isolating piezoelectric element 19.21 and the variable coil 23.25 becomes completely anti-resonant with respect to vibrations with a frequency of about 28 [KHz], and the mechanical member M This suppressed mechanical vibrations to the point where they could no longer be measured.

With the vibration isolating device of the first embodiment described above, even if the frequency of mechanical vibration generated in the mechanical member M is as high as about 28 KHz, the mechanical The amplitude of vibration generated in member M per input voltage is o, o O2 [μm/V], even if we look at the minimum value that could be measured.
+2 can be suppressed and no vibration isolation was performed, solid line B
The amplitude of vibration per input voltage shown in is 0.132 [μm
/V] It is possible to suppress the amplitude of the mechanical vibration of the mechanical member M to 1/60 or less, which is an excellent effect.

Even if the frequency of the mechanical vibrations generated in the mechanical member M is low, the anti-resonance frequencies of the parallel circuits can be matched by adjusting the capacitance of the piezoelectric element 1 and the inductance of the variable coil 3ff. Since the mechanical vibration generated in the mechanical member M can be suppressed, this vibration isolator has the effect of suppressing mechanical vibration regardless of the frequency.

Further, according to the vibration isolating device of the first embodiment, the mechanical member M
Even if the frequency of mechanical vibration occurring in the machine is not accurately known, by adjusting the inductance of the variable coil 3, the anti-resonance frequency of the parallel circuit can be made to match the mechanical torsion of the mechanical member M. Since the mechanical vibrations generated in the member M can be suppressed, the effect is that it is extremely easy to use.

Furthermore, since the circuit constituted by the piezoelectric element 1 and the variable coil 3 does not consume power, there is no need for an electric circuit, which is advantageous.

(Second Embodiment) Second Embodiment (It has conductivity like the first embodiment!)
! ! The vibration of the mechanical member M is suppressed by a plurality of piezoelectric elements 3 bonded to the mechanical member M, as shown in FIG.
1, 33, 35. 37 and a coil 39. of different inductance connecting the top surface of each piezoelectric element and the surface of the i+t member M. 4+, 43.45.

Each piezoelectric element 31, 33, 35, 371 is made of zircon-lead titanate (PZT), etc., as in the first embodiment, and has electrodes on the upper and lower surfaces of each piezoelectric element.

The upper electrode (open side) is the coil 39, 41, 43.4
5, but the electrode on the bottom surface (mechanical member M side)
is electrically connected to the mechanical member M, and is electrically connected to the variable coil via the mechanical member M.

Each coil 39, 41, 43, 451 companies Number of turns of coil
By changing the cross-sectional area, the length of the magnetic path, the extent to which the core moves in and out, etc., each inductance is adjusted to be different, and the inductance value differs by a predetermined value.

The vibration isolator of the second embodiment constructed in this manner {secondly,
Since the capacitance of each piezoelectric element 31, 33, 35.37 and the anti-resonance frequency of each parallel circuit constituted by each coil 39, 41, 43.45 differ by a predetermined value, among the parallel circuits, Its anti-resonant frequency is a! A piezoelectric element in a parallel circuit that substantially matches the frequency of the mechanical vibration suppresses the mechanical vibration of the mechanical member M. Focusing on the circuit portion constituted by the individual piezoelectric elements and coils (2) This is because, as in the first embodiment, if the anti-resonance frequency substantially matches the mechanical vibration, it will behave to suppress the mechanical vibration.

As explained above, due to the vibration isolating device of the second embodiment, {L
Even if the frequency of the mechanical vibration generated in the mechanical member M12 is over a wide range of frequencies, an excellent effect is achieved in that the mechanical vibration generated in the mechanical member M can be significantly suppressed.

In addition, since multiple circuits with different anti-resonance frequencies are constructed using coils with different inductances, the frequency generated in the mechanical member M! If it is not precisely known or
Even if the frequency of the mechanical vibrations generated in the mechanical member M is slightly fluctuated, the vibrations can be reliably suppressed, resulting in an extremely convenient usability.

Furthermore, piezoelectric elements 31, 33, 35. 37
Since the circuit constituted by Yuil 39, 4+, 43, and 45 does not consume power, there is also an advantage that no power supply circuit is required as in the first embodiment.

(Third Embodiment) In this embodiment, a vibration isolator is applied to an ultrasonic motor. Figure 6 shows the cross section of the ultrasonic motor of this embodiment.
The figure is a perspective view of the mover.

As shown in FIG. 6, this ultrasonic motor is a standing wave type rotary motor, which includes an ultrasonic vibrator 53 installed in a housing 51, and a movable element 55 rotatably supported by the housing 51. An output shaft 57 is integrally provided in the movable element 55. A compression spring 59 is interposed between the housing 51 and the movable element 55, and the movable element 5
5 is pressed against the ultrasonic transducer 53.

Ultrasonic transducer 53 (upper) has a disk shape.

On its lower surface, bending vibration in the axial direction due to the piezoelectric element 51 attached to the outer annular protrusion 53a and inner annular protrusion 53
It is provided with a configuration that excites the elliptical motion of the mass point by overlapping with the circumferential shear vibration caused by the piezoelectric element 53 attached to b. An AC high voltage generating circuit is connected to each of the piezoelectric elements 51, 53 mentioned above. Note that the elastic modulus and shape of the ultrasonic vibrator 53 are adjusted in order to generate ultrasonic vibrations of a predetermined frequency.

The mover 55 has a disk shape as shown in FIG.
An output shaft 57 is integrally provided in the center. A contact portion 55a that comes into contact with the ultrasonic transducer 53 is provided on the outer edge of the bottom surface. A vibration isolator 64 is attached to this movable element 55.

Vibration isolating device 641 consists of an annular piezoelectric element 65 attached to the upper surface 55b of the movable element 55, and a variable coil 67 connected to the piezoelectric element 65 and the movable element 55. The anti-resonance frequency of the parallel circuit constituted by the capacitance of the piezoelectric element 65 and the variable coil 67 is matched to the frequency of the ultrasonic vibration generated by the ultrasonic vibrator 53.

The piezoelectric element 65 is made of zircon-lead titanate (PZT) or the like, and has electrodes on both sides thereof.

The electrode on the front surface (open surface) side is directly connected to the variable coil 67, but the electrode on the back surface (mounting surface) side is electrically connected to the movable element 55, so that the electrode is connected to the variable coil 67 via the conductive movable element 55. Electrical conduction with the variable coil 67 is attempted. In addition, the mover 5
If 5 is made of a non-conductive material (the electrode on the back side is also variable), it may be configured to be directly connected to the coil 37.

Variable coil 671,t This is a coil equipped with a variable mechanism that changes its inductance by adjusting the insertion and removal of the core.

In the ultrasonic motor configured in this way, when ultrasonic vibrations of a predetermined frequency are excited in the ultrasonic vibrator 53 and elliptical motion is generated at each mass point on the surface on the movable element 55 side,
Each of the mass points contacts the contact portion 55a1 of the mover 55 for a minute time, and the friction of the contact surface causes the mover 55 to move over a minute distance.
Repeat the movement. In this way, the movable element 55 is continuously rotated, and the output shaft 57 formed integrally therewith is rotated.

At this time, if the mover 55 resonates due to the action of ultrasonic vibration, the ultrasonic vibrator 53 will not be able to make sufficient contact with the mover 55, and the force based on the ultrasonic vibration will not be effectively transmitted to the mover 55. A stable state may occur, or energy may leak to the outside due to vibration of the movable element 55 itself.

In the ultrasonic motor of this embodiment, when the mover 55 starts to vibrate due to ultrasonic vibration, the vibration isolator 64 attached to the mover 55 stops the vibration of the mover 55 at the beginning of the vibration. In other words, when the piezoelectric element 65 receives the vibration of the movable element 55 and tries to generate a voltage output with the same frequency as the vibration of the movable element 55, the capacitance of the piezoelectric element 65 and the parallel circuit constituted by the variable coil 67 behaves similarly to the first embodiment and prohibits deformation of the piezoelectric element 65.

As a result, vibration of the movable element 55 to which the piezoelectric element 65 is attached is suppressed.

By using an ultrasonic motor to which the vibration isolator described above is applied (
ヱ Vibration of the movable element 55 is prevented. The ultrasonic vibrator 53 makes good contact with the movable element 55 and efficiently transmits the force based on the ultrasonic vibration due to the friction of the contact surface, so that the movable element 55 can be rotated. It has excellent effects.

In addition, the vibration isolator 64 (upper piezoelectric element 65 and variable coil 6
Since the structure of 7 is extremely simple, the shape is small and the quality is light, the mover 5 has a limited installation space.
5 and the housing 51 without any problems, and does not affect the dynamic characteristics of the motor.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments in any way, and it goes without saying that the present invention can be implemented in various forms without departing from the gist of the present invention. For example, the electromechanical conversion element may be any element that can convert energy from mechanical vibration into electrical vibration, such as an electrostrictive element or a magnetostrictive element. An impedance element (a configuration in which a variable capacitance 71 is connected in parallel to a coil 73 as shown in Fig. 8 above) may also be used. The impedance element may include a small resistance component.

Effects of the Invention As detailed above, the vibration isolating device of the present invention
An extremely simple configuration consisting of a conversion element and an impedance element provides an excellent effect of reliably suppressing mechanical vibrations generated in mechanical members.

Furthermore, since it is an extremely small device, only a small amount of space is required for installation, and it can be installed in any location, making it extremely easy to use.

Furthermore, since the circuit constituted by the electromechanical transducer and the impedance element does not consume power, there is no need for a power supply circuit, which is advantageous.

[Brief explanation of drawings]

Figure 1 shows the configuration of a vibration isolator as a first embodiment of the present invention.
Figure 2 is the electrical equivalent circuit, Figure 3 is a perspective view of the experimental equipment, Figure 4 is a graph showing the experimental results, Figure 5 is the configuration of the vibration isolator as the second embodiment, Figure 6 7 is a cross section of an ultrasonic motor to which the vibration isolating device of the third embodiment is applied. FIG. 7 is a perspective view of the movable element. FIG. 8 is a circuit diagram showing another example of the impedance element. 1 (31, 33, 35.37)...Piezoelectric element 3
(39, 41, 43. 45)...Coil M...
Mechanical member 53... Ultrasonic transducer 55-... Mover 61.
63...Piezoelectric element for vibration excitation

Claims (1)

[Scope of Claims] 1. A vibration isolating device that suppresses mechanical vibrations generated in a mechanical member, comprising: an electromechanical transducer that is attached to the mechanical member and converts the energy of mechanical vibrations and electrical vibrations; an impedance element that is connected to the mechanical transducer and forms a closed circuit together with the electromechanical transducer; the reactance component of the electromechanical transducer and the anti-resonance frequency of the parallel circuit formed by the impedance element are converted to the anti-resonant frequency of the mechanical member; A vibration isolating device characterized by having a frequency that substantially matches the frequency of mechanical vibration.