JP2697149B2 - Anti-vibration device - Google Patents

Description

Description: Object of the Invention [Industrial application field] The present invention relates to an anti-vibration device, and more particularly to an anti-vibration device for suppressing mechanical vibration generated in a mechanical member.

[Prior art] As a conventional vibration isolating device, for example, a device that suppresses mechanical vibration by absorbing vibration energy by using a vibration isolating rubber, or analyzes a phase and an amplitude of the mechanical vibration to obtain a mechanical vibration. There is a device that suppresses mechanical vibration by externally applying vibration having a phase opposite to that of mechanical vibration to a mechanical member.

[Problem to be Solved by the Invention] However, the above-described configuration has a problem that mechanical vibration generated in a mechanical member may not be suppressed in some cases.

For example, in the former device using the vibration damping rubber, the effect of suppression can be obtained over a wide frequency band, but on the other hand, there is a problem that vibration of a specific frequency such as low frequency vibration cannot be suppressed.

In the latter device for applying vibration from the outside, there is a problem that it is necessary to adopt a difficult configuration in which a vibration having the opposite phase is applied from the outside in synchronization with the phase of the vibration.
In addition, this device requires the use of an actuator that applies vibration from the outside, a sensor that detects vibration, and a control circuit that can perform high-speed arithmetic processing. However, there has been a problem that a relatively large space is required for installation due to the adoption of the system, and the application location is restricted.

An object of the present invention is to solve the above-mentioned problem and to surely suppress mechanical vibration of a mechanical member.

Configuration of the Invention The configuration of the present invention that achieves the above object will be described below.

[Means for Solving the Problems] A vibration damping device according to the present invention is a vibration damping device for suppressing mechanical vibration generated in a mechanical member, which is attached to the mechanical member and converts energy of mechanical vibration and electric vibration. , And an impedance element connected to the electromechanical conversion element and forming a closed circuit together with the electromechanical conversion element, wherein a reactance component of the electromechanical conversion element and a parallel component formed by the impedance element are provided. The anti-resonance frequency of the circuit is substantially equal to the frequency of the mechanical vibration of the mechanical member.

[Operation] In the vibration damping device of the present invention having the above configuration, the electromechanical transducer mounted on the mechanical member is deformed in accordance with the mechanical vibration of the mechanical member, and generates an electrical output having the same frequency as the mechanical vibration. If you try, it behaves as follows. Since the antiresonance frequency of the parallel circuit formed by the reactance component and the impedance element of the electromechanical transducer is substantially equal to the frequency of the mechanical vibration to be suppressed by the mechanical member, the parallel circuit is connected to the output end of the electromechanical transducer. No current flows.
The amount of deformation of the electromechanical transducer is proportional to the magnitude of the current at the output end, but as a result no current flows at the output end,
Deformation of the electromechanical transducer is prohibited, and mechanical vibration of the mechanical member is suppressed.

Embodiment In order to further clarify the configuration and operation of the present invention described above, a preferred embodiment of the vibration isolator of the present invention will be described below.

(First Embodiment) FIG. 1 is a configuration diagram of a vibration isolator according to a first embodiment of the present invention.

This vibration isolator suppresses vibration of the mechanical member M having conductivity. It comprises a piezoelectric element 1 bonded to a mechanical member M, and a variable coil 3 connected to the upper surface 1a of the piezoelectric element 1 and 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. While the electrode 5 on the upper surface 1a is directly connected to the variable coil 3, the electrode 7 on the lower surface 1b is electrically connected to the mechanical member M, thereby achieving conduction with the variable coil 3 via the mechanical member M. I have.

The variable coil 3 is a coil provided with a variable mechanism that changes its inductance by adjusting the movement of the core.

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

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

However, in the variable coil 3, the energy stored in the inductance component is larger than the energy consumed in the resistance component in one cycle.

In the vibration damping device of the present embodiment thus configured, the piezoelectric element 1 receives the vibration of the mechanical member M and generates a voltage output having the same frequency as the mechanical vibration of the mechanical member M. The parallel circuit 14 formed by the capacitance 13 of the piezoelectric element 1 and the variable coil 3 attached to the outside has an anti-resonance frequency equal to the frequency of the mechanical vibration of the mechanical member M. The current flowing through the variable coil 13 is a large current whose phase is advanced by 90 degrees with respect to the change in the voltage output with the force coefficient 11, while the current flowing through the variable coil 3 is 90 degrees with respect to the change in the voltage output with the force coefficient 11 A large current is delayed. Since only energy is exchanged between these two elements, no current flows at a force coefficient of 11. That is, even if a voltage output is generated due to mechanical vibration, no current flows through the force coefficient 11, so that the mechanical vibration amplitude cannot be converted to a current output. In other words, at this time, the deformation of the piezoelectric element 1 is prohibited, and the mechanical vibration of the mechanical member M is suppressed.

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

A rectangular parallelepiped brass member was used as the mechanical member M. The dimensions are length L1 = 60 [mm], width W1 = 20 [mm], thickness T1 = 16
[Mm]. Piezoelectric elements 15 and 17 for exciting vibration were bonded to two parallel surfaces at the ends of the mechanical member M. The dimensions of the vibration excitation piezoelectric elements 15 and 17 are as follows: length L2 = 23 [m
m], width W2 = 13 [mm], and thickness T2 = 1 [mm]. An AC high-voltage generating circuit was connected to the vibration-exciting piezoelectric elements 15 and 17 to excite the mechanical member M with a longitudinal vibration that expands and contracts in the major axis direction at a frequency of about 28 [KHz].

At the other end of the mechanical member M configured in this manner, two piezoelectric elements 19 and 21 as a vibration isolator are attached.
Bonded to the same two surfaces as 5,17. The dimensions of the anti-vibration piezoelectric elements 19 and 21 are length L3 = 25 [mm], width W3 = 6 [mm], and thickness T3 = 2
[Mm]. The bottom surfaces of the vibration isolating piezoelectric elements 19 and 21 were electrically connected to the mechanical member M, and the variable coils 23 and 25 were connected between the upper surface and the surface of the mechanical member M.

The experiment was performed by measuring the amplitude of the mechanical vibration of the mechanical member M while gradually changing the inductance of the variable coils 23 and 25 of the vibration isolator.

FIG. 3 is a graph showing the results of the experiment. The horizontal axis is the magnitude of the inductance of the variable coils 23 and 25, and the vertical axis is the mechanical member M per voltage input to the piezoelectric elements 15 and 17 for vibration excitation.
Shows the amplitude of mechanical vibration actually generated. In the figure, a solid line A indicates a case where the vibration isolation by the vibration isolator was performed, and a solid line B indicates a case where the vibration isolation was not performed. From the solid line A, the variable coil
It can be seen that when the inductance of 23, 25 is in the range of 17 [mH] to 20 [mH], the amplitude of the vibration generated per input voltage to the machine member M is minimized. Inductance is 19
The reason why the solid line A is not drawn in the range in the vicinity of [mH] is that the amplitude becomes extremely small and measurement becomes impossible. That is, when the inductance of the variable coils 23 and 25 is around 19 [mH], the capacitance of the piezoelectric elements 19 and 21 and the variable coil 2 are reduced.
The parallel circuit constituted by the components 3 and 25 is in a completely anti-resonant state with respect to the vibration having a frequency of about 28 [KHz], and the mechanical vibration of the mechanical member M is suppressed to such an extent that it cannot be measured.

According to the vibration isolator of the first embodiment described above, even if the frequency of the mechanical vibration generated in the mechanical member M is as high as about 28 [KHz], as shown by the solid line A in the graph of FIG. The amplitude of the vibration generated per input voltage on the mechanical member M can be suppressed to 0.002 [μm / V] even if the measured minimum value is seen.
Excellent in that the amplitude of the mechanical vibration of the mechanical member M can be suppressed to 1/60 or less as compared with the amplitude of the vibration per input voltage of 0.132 [μm / V] indicated by the solid line B in which the vibration isolation is not performed. It has the effect. Of course, even if the frequency of the mechanical vibration generated in the mechanical member M is low, if the capacitance of the piezoelectric element 1 and the inductance of the variable coil 3 are adjusted to match the anti-resonance frequency of the parallel circuit, the mechanical member can be changed. Since the mechanical vibration generated in M can be suppressed, the vibration isolator has an effect that the mechanical vibration can be suppressed regardless of the frequency.

According to the vibration isolator of the first embodiment, even if the frequency of the mechanical vibration generated in the mechanical member M is not accurately known, the inductance of the variable coil 3 is adjusted so that the parallel circuit Can be matched with the mechanical vibration of the mechanical member M, and the mechanical vibration generated in the mechanical member M can be suppressed.

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

(Second Embodiment) The second embodiment suppresses the vibration of the mechanical member M having conductivity similarly to the first embodiment, but is bonded to the mechanical member M as shown in FIG. Multiple piezoelectric elements 31, 33,
35, 37 and coils 39, 41, 43, 45 having different inductances for connecting the upper surface of each piezoelectric element and the surface of the mechanical member M.

Each of the piezoelectric elements 31, 33, 35 and 37 is made of zircon / lead titanate (PZT) or the like as in the first embodiment, and has electrodes on the upper and lower surfaces of each piezoelectric element. The upper electrode (open side) is directly connected to the coils 39, 41, 43, 45, while the lower electrode (mechanical member M side) is electrically connected to the mechanical member M. Conduction with the variable coil is achieved through the switch.

Each of the coils 39, 41, 43, and 45 is adjusted to a different inductance by changing the number of turns of the coil, the cross-sectional area, the length of the magnetic path, the degree of entering and exiting the core, and the like. Values are different.

In the vibration isolator of the second embodiment configured as described above,
The capacitance of each piezoelectric element 31, 33, 35, 37 and each coil 39, 4
Since the anti-resonance frequencies of the parallel circuits formed by 1, 43, and 45 differ from each other by a predetermined value, the piezoelectric element of the parallel circuit whose anti-resonance frequency substantially matches the frequency of mechanical vibration is included in the parallel circuit. The mechanical vibration of the mechanical member M is suppressed. If attention is paid to the circuit portion formed by each piezoelectric element and coil, as in the first embodiment, if the anti-resonance frequency substantially coincides with the mechanical vibration, the circuit acts to suppress the mechanical vibration.

As described above, according to the vibration isolator of the second embodiment,
Even if the frequency of the mechanical vibration generated in the mechanical member M extends over a wide frequency range, an excellent effect that the mechanical vibration generated in the mechanical member M can be suppressed remarkably can be obtained.

In addition, since a plurality of circuits having different anti-resonance frequencies are configured using coils having different inductances, when a frequency generated in the mechanical member M is not accurately known,
Even when the frequency of the mechanical vibration generated in the mechanical member M is slightly fluctuated, the vibration can be surely suppressed, and the effect that the usability becomes extremely good is exhibited.

Further, the piezoelectric elements 31, 33, 35, 37 and coils 39, 41, 43,
Since the circuit constituted by 45 does not consume power, there is an advantage that a power supply circuit is not required as in the first embodiment.

(Third Embodiment) In this embodiment, a vibration isolator is applied to an ultrasonic motor. FIG. 6 is a sectional view of the ultrasonic motor according to the present embodiment, and FIG. 7 is a perspective view of the mover.

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

The ultrasonic transducer 53 has a disk shape. On its lower surface, a piezoelectric element 51 attached to the outer annular projection 53a
, And the elliptical motion of the mass point is excited by the overlap of the axial bending vibration due to and the circumferential shear vibration by the piezoelectric element 53 attached to the inner annular convex portion 53b. An AC high voltage generating circuit is connected to each of the piezoelectric elements 51 and 53 described above. The elasticity and shape of the ultrasonic transducer 53 are adjusted in order to generate ultrasonic vibration of a predetermined frequency.

The mover 55 has a disk shape as shown in FIG. 7, and has an output shaft 57 integrally provided at the center. The outer edge of the bottom surface is provided with a contact portion 55a that comes into contact with the ultrasonic transducer 53.
A vibration isolator 64 is attached to the mover 55.

The anti-vibration device 64 includes an annular piezoelectric element 65 attached to the upper surface 55b of the mover 55, and a variable coil 67 connected to the piezoelectric element 65 and the mover 55. Piezoelectric element
The anti-resonance frequency of the parallel circuit formed by the capacitance of 65 and the variable coil 67 matches 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 surfaces. The electrode on the front surface (open surface) is directly connected to the variable coil 67, while the electrode on the back surface (mounting surface) is electrically connected to the mover 55, so that the Conduction with the variable coil 67 is achieved. When the mover 55 is made of a non-conductive material, the electrode on the back side may be directly connected to the variable coil 37.

The variable coil 67 is a coil provided with a variable mechanism that changes its inductance by adjusting the ingress and egress of the core.

In the ultrasonic motor configured as described above, when ultrasonic vibration of a predetermined frequency is excited in the ultrasonic vibrator 53 and elliptic motion occurs at each mass point on the surface on the movable element 55 side, each of the mass points moves. Contact the contact portion 55a of the child 55 for a very short time,
The operation of moving the mover 55 by a very small distance due to the friction of the contact surface is repeated. Thus, the mover 55 is continuously rotated, and the output shaft 57 integrally formed therewith is rotated.

At this time, if the mover 55 resonates due to the action of the ultrasonic vibration, the ultrasonic vibrator 53 cannot sufficiently contact the mover 55, and the force based on the ultrasonic vibration is not effectively transmitted to the mover 55. A stable state occurs, and energy leaks to the outside due to vibration of the mover 55 itself.

In the ultrasonic motor according to the present embodiment, when the ultrasonic vibration acts and the mover 55 starts to vibrate, the vibration isolator 64 attached to the mover 55 at the beginning of the vibration suppresses the vibration of the mover 55. I do. That is, the piezoelectric element receives the vibration of the mover 55
When the 65 attempts to generate a voltage output having the same frequency as the vibration of the mover 55, the capacitance of the piezoelectric element 65 and the parallel circuit formed by the variable coil 67 behave similarly to the first embodiment,
The deformation of the piezoelectric element 65 is prohibited. As a result, vibration of the mover 55 to which the piezoelectric element 65 is attached is suppressed.

According to the ultrasonic motor to which the vibration isolator described above is applied, the vibration of the mover 55 is prevented, and the ultrasonic vibrator 53 is in good contact with the mover 55 and is based on the ultrasonic vibration due to the friction of the contact surface. An excellent effect of efficiently transmitting force and rotating the mover 55 is achieved.

In addition, since the vibration isolator 64 has a very simple configuration of the piezoelectric element 65 and the variable coil 67, and has a small shape and a light weight, there is nothing between the housing 51 of the mover 55 having a limited installation space. It can be mounted without any trouble 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 at all, and it goes without saying that the present invention can be implemented in various modes without departing from the gist of the present invention. For example, the electromechanical transducer may be any element that can convert mechanical vibration into electric vibration, such as an electrostrictive element or a magnetostrictive element. The impedance element may have a configuration in which a variable capacitance 71 is connected in parallel to a coil 73 as shown in FIG. The parallel circuit formed by the reactance component and the impedance element of the electromechanical conversion element is substantial, and the impedance element may include a small resistance component.

Effects of the Invention As described in detail above, the vibration damping device of the present invention has an excellent effect that mechanical vibration generated in a mechanical member can be reliably suppressed by an extremely simple configuration including an electromechanical transducer and an impedance element. Play.

In addition, since the device is extremely small, only a small space is required for installation, and the device can be installed at any location, so that there is an effect that the usability becomes extremely good.

Further, since the circuit formed 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 description of the drawings]

FIG. 1 is a configuration diagram of a vibration isolator as a first embodiment of the present invention,
FIG. 2 is an electrical equivalent circuit thereof, FIG. 3 is a perspective view showing the experimental apparatus, FIG. 4 is a graph showing experimental results, FIG. 5 is a configuration diagram of a vibration isolator as a second embodiment, FIG. FIG. 6 is a cross-sectional view of an ultrasonic motor to which the vibration damping device according to the third embodiment is applied, FIG. 7 is a perspective view of the mover, and 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 ... movable element 61, 63 ... Piezoelectric element for vibration excitation 65… Piezoelectric element for vibration isolation, 67 …… Variable coil

Claims (1)

(57) [Claims] 1. An anti-vibration device for suppressing mechanical vibration generated in a mechanical member, an electromechanical conversion element attached to the mechanical member and performing energy conversion of mechanical vibration and electric vibration; An impedance element connected to the element and forming a closed circuit together with the electromechanical conversion element, wherein the reactance component of the electromechanical conversion element and the anti-resonance frequency of the parallel circuit formed by the impedance element are determined by the mechanical An anti-vibration device characterized by being substantially matched to a vibration frequency.