JPH07180744A - Natural frequency variable type vibration damping device - Google Patents

Abstract

PURPOSE:To facilitate design for the natural frequency variable type vibration damping device which is most suitable to industrial machines and the like by providing springs supporting a mass body in such a way as to be laterally symmetric with respect to a guide shaft, and concurrently providing a natural frequency variable means which changes a spring constant by changing the mounting angle of each spring and the like. CONSTITUTION:A mounting base 41 is fixed on the upper surface of a vibrated object, and both the ends of a screw shaft 44 where its left half is formed into a left handed screw 44L, and its right half is formed into a right handed crew 44R, are rotatably supported by paired right and left support brackets 42 vertically erected over the mounting base 41. An elasticity adjusting motor 52 as a natural frequency variable means is also provided over the mounting base 41 via a bracket 51, and a pinion 53 fixed on the output shaft of the motor 52 is meshed with a gear 50 fixed on the screw shaft 44. The synthetic elastic modulus (spring constant) of springs 55L and 55R supporting the mass body 47, that is, natural frequency is thereby changed by moving right and left nuts 49L and 49R in the approaching/parting directions with the screw shaft 44 rotated by the operation of the motor 52.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a natural frequency variable type vibration damping device for damping the vibration of an object which is vibrated by receiving a vibrating force. The present invention relates to a variable natural frequency type vibration damping device that is optimal for general-purpose equipment.

[0002]

2. Description of the Related Art It has long been known that a dynamic vibration reducer is effective as a vibration control method for an object to be vibrated which is vibrated by a periodic excitation force. This is because a vibrating object is equipped with a device consisting of a spring, a mass, a damper, etc., having a natural frequency equal to the frequency of the exciting force, and the vibrating force of this device is used to counteract the vibrating object near its actual vibration frequency. It absorbs and suppresses vibration so that a resonance point is formed. However, this method has a problem that the vibration frequency and the natural frequency of the dynamic vibration absorber need to match with each other with high accuracy, and cannot be applied when the vibration frequency changes.

Therefore, various natural frequency variable type vibration damping devices have been proposed in which the natural frequency changes in synchronization with the change in the frequency of the exciting force to absorb the vibration.

As such a vibration damping device, Japanese Patent Laid-Open No. 56-
43174 and the one disclosed in Japanese Patent Laid-Open No. 3-247872 are known. The former is applied to the vibration control of a cantilever type structure, and as a spring having a natural frequency, a leaf spring is aligned with the above cantilever type structure so that the cantilever type structure is free. It is a cantilever type vibration damping device attached to an end and provided with a weight slidable on the spring. In the vibration damping device having such a structure, the weight on the spring is slid to change the natural frequency of the spring so as to be synchronized with the change in the frequency of the exciting force to obtain the vibration absorbing effect.

The latter is applied to suppress the vibration of a building due to an earthquake or a strong wind, and the inertial mass body is supported by the first and second springs that vibrate in the same direction. Has a fixed spring constant, and the second spring is a vibration damping device with a variable spring constant. The vibration damping device having such a structure obtains a vibration absorbing effect by changing the spring constant of the second spring so as to be synchronized with the change in the frequency of the exciting force.

[0006]

However, in the former case, since the cantilever shape is used, a moment is generated at the leaf spring mounting portion, and the mounting angle between the cantilever structure and the spring is large for the vibration absorbing effect. It became clear that it would affect. Therefore, in order to improve the vibration absorption effect, it is necessary to change the mounting angle of the leaf spring along with the sliding of the weight on the spring. There is a problem that the number of designs increases and the design becomes complicated.
Further, in the latter case, the target purpose is enormous in order to suppress the vibration of the building due to the earthquake or the strong wind, so that the device itself becomes large and is not suitable for general-purpose equipment such as industrial machines and construction machines.

The variable vibration frequency type vibration damping device of the present invention has been made in view of the above problems. The purpose of the vibration damping device is to prevent the occurrence of a moment in the mounting portion to complicate the design. The present invention is intended to provide a variable number type vibration damping device.

[0008]

In order to solve the above-mentioned problems, a natural frequency variable type vibration damping device of the present invention comprises a mounting base, a guide shaft vertically provided at the center of the mounting base, and A mass body slidably attached to the guide shaft, and a spring that has one end attached to the mass body and the other end attached to the mounting base side and that is symmetrical with respect to the guide shaft and that supports the mass body. A natural vibration in which the position of the other end of the symmetrical spring is moved along the mounting base and the angle of the spring with respect to the mounting base is symmetrically changed to change the spring constant and to change the natural frequency. The number variable means is provided.

Further, the natural frequency variable type vibration damping device of the present invention includes guide shafts vertically installed on both end sides of the mounting base,
By moving a mass body that is slidably inserted in common with the guide shaft, a symmetrical cantilever-shaped plate spring that supports the mass body, and a mass body supporting point of the plate spring. The natural frequency changing means for changing the spring constant to change the natural frequency is provided.

[0010]

[Function] A spring supporting the mass body is provided symmetrically with respect to the guide shaft to change its mounting angle, and a cantilever plate spring supporting the mass body is provided symmetrically with respect to the guide spring. When the natural frequency changing means for changing the natural frequency by changing the spring constant by moving the mass support point is provided, the natural frequency can be adjusted in synchronization with the change in the frequency of the exciting force. Since the spring supporting the mass body does not generate a moment in the mounting portion, the design does not become complicated.

[0011]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a diagram showing a natural frequency variable type vibration control device 40 which is a first embodiment of the present invention. The natural frequency variable type vibration control device 40 of the present invention includes the mounting base 4
1 and a guide shaft 46 which is erected vertically in the center of the mounting base.
And a mass body 47 slidably attached to the guide shaft 46.
And springs 55L and 55R that are symmetric with respect to the guide shaft 46 that has one end attached to the mass body 47 and the other end attached to the mounting base 41 side and supports the mass body 47, and the symmetric springs 55L and 55R. A natural frequency changing means for changing the natural frequency by changing the spring constant by moving the position of the other end along the mounting base 41 and changing the angle of the springs 55L and 55R with respect to the mounting base 41. 5
Equipped with 2. The reason why the springs that support the mass body are provided symmetrically with respect to the guide shaft is that a moment is not generated in the mounting portion. The spring constants of the symmetrical springs are the same.

Further, each member will be described in detail. In the figure, a mounting base 41 is fixed to the upper surface of the object to be vibrated, and a pair of left and right support brackets 42 are erected on the mounting base 41. Both ends are rotatably supported. A left screw 44L is formed on the left half of the screw shaft 44, and a right screw 44R is formed on the right half thereof, and a gear 50 is fixed to a substantially intermediate portion of the screw shaft 44. An elastic adjusting motor (natural frequency changing means) 52 is adjusted on the mounting base 41 via a bracket 51, and a pinion 53 is fixed to an output shaft of the natural frequency changing means 52.
The pinion 53 is meshed with the gear 50.

A bracket 45 straddling the central portion of the screw shaft 44 is installed at the center of the mounting base 41, and a vertical guide shaft 46 is erected on the bracket 45. The guide shaft 46 includes a mass body 47 formed of a material having a relatively large specific gravity such as iron. The linear bearing 4 is provided between the mass body 47 and the guide shaft 46.
8 is provided, and the mass body 47 can be moved up and down while being guided by the guide shaft 46.

A nut 49L is screwed into the left screw 44L of the screw shaft 44 and a nut 49R is screwed into the right screw 44R. The nut 49L and the lower surface of the left wing of the mass body 47 are connected via a coil spring 55L. Connected, nut 4
9R and the lower surface of the right wing portion of the mass body 47 are coil springs 55.
It is connected through R.

Therefore, in the natural frequency variable type vibration control device 40 of the present invention, the screw shaft 44 is rotationally driven by the operation of the natural frequency variable means 52, and with the rotation of the screw shaft 44, the left and right nuts 49L, By moving the 40R in the direction of approaching and separating from each other (see the solid line and the chain double-dashed line in FIG. 1),
The composite elastic coefficient (spring constant) K of the springs 55L and 55R supporting the mass body 47 is changed.

The eigenfrequency variable type vibration control device 40 of the present invention constructed as described above measures the actual vibration frequency f of the vibrated object which is vibrated by the excitation force by a measuring device (not shown). Then, K = 4π ² · f · so that the natural frequency is such that an anti-resonance point is formed near the vibration frequency.
m (Equation 1) is used to obtain the composite elastic coefficient (spring constant) K, and based on the obtained K, K = 2k / sin θ (Equation 2) is used to determine the angle θ of the springs 55L and 55R with respect to the mounting base 41, and the angle In order to obtain θ, the elasticity adjusting motor (natural frequency changing means) 52 is controlled and operated by the control means (not shown). Here, m is the mass of the mass body 47, and k is the original spring constant of the springs 55L and 55R.

Next, a second embodiment will be described with reference to FIG. Another natural frequency variable type vibration control device 7 according to the present invention
Reference numeral 0 denotes a mounting base 71, a guide shaft 75 vertically provided on both end sides of the mounting base 71, a mass body 72 slidably inserted in common to the guide shaft 75, and a mass body 72. Left and right symmetrical cantilevered leaf springs 80 and leaf springs 8
There is provided a natural frequency changing means for changing the natural frequency by changing the spring constant by moving the mass body support point of 0. The reason why the leaf springs that support the mass body are symmetrically provided in this manner is that a moment is not generated in the mounting portion. In addition, the spring constants of the left and right symmetrical leaf springs are the same.

Further, each member will be described in detail. In the figure, the base 71 is fixed to the upper surface of the object to be vibrated. The upper part of each guide shaft 75 erected on the base 71 penetrates a common restricting plate 76, and the restricting plate 76 is a nut 74 to which a screw 75a formed on the upper part of each guide shaft 75 is attached.
The upward movement is restricted by. A coil spring 78 is provided in a compressed state between the lower surface of the mass body 72 and the upper surface of the base 71, and between the mass body 72 and the regulation plate 76. It is supported in a floating state.

Spring mounting portions 79 attached to both left and right wings of the base 71 are erected, and the base ends of the leaf springs 80, which are cantilevers, are fixed to the leaf spring mounting portions 79. The ends are facing each other in the center.

On the other hand, a guide 81 extending left and right is provided on the lower surface of the mass body 72, and a pair of left and right nuts 82L and 82R are provided slidably along the guide 81. A roller 83 running on the leaf spring 80 is connected. Bearing portions 84 are provided on the lower surfaces of the left and right wings of the mass body 72.
The left and right ends of the screw shaft 85 are rotatably supported by. The left half of this screw shaft 85 has a left screw 85L,
A right screw 85R is formed on the right half portion, and the nut 82L is screwed to the left screw 85L and the nut 82R is screwed to the right screw 85R. The gear 8 is located at the center of the screw shaft 85.
6 is fixed, an elastic adjusting motor (natural frequency varying means) 87 is provided in the mass body 72, and the pinion 88 fixed to the elastic adjusting motor (natural frequency varying means) 87 is the above-mentioned. It is meshed with the gear 86.

Therefore, in the natural frequency variable type vibration control device 70, the elasticity adjusting motor (natural frequency variable means) 8 is used.
When the screw shaft 85 is rotationally driven by the operation of 7, the nuts 82L and 82R and the rollers 83 are displaced in a direction in which the nuts 82L and 82R come into contact with and separate from each other. Has become.

The reason why the mass body 72 is made to float by the coil spring 78 is as follows. When the mass body 72 is supported only by the leaf spring 80, it is necessary to increase the rigidity of the leaf spring 80. However, another natural frequency variable type vibration control device 70 according to the present invention has a mass body supporting point of the leaf spring 80. Since the spring constant is changed by moving the to change the natural frequency, if the rigidity of the leaf spring 80 is increased, the moving distance for changing the spring constant becomes long, and the entire device becomes large. I will end up. Then, there arises a problem that fine adjustment for changing the natural frequency of the device also becomes difficult. Therefore, the mass body 72 is kept in a floating state by the coil spring 78 having a fixed spring constant.

From the viewpoint of the above reason, also in the first embodiment shown in FIG. 1, if the mass body 47 is supported only by the springs 55L and 55R, the moving distance for changing the spring constant becomes long. When the size of the entire device becomes large and fine adjustment for changing the natural frequency of the device becomes difficult, a coil spring having a fixed spring constant is inserted into the guide shaft 46 to float the mass body 47. In this state, the spring constants of the springs 55L and 55R can be changed to make fine adjustments to change the natural frequency of the device.

Further, as shown in FIG.
By interposing a viscoelastic vibration absorber such as the dashpot 90 between the control plate 76 and the control plate 76, the vibration of the vibrating body 72 and the cab 20 can be damped more quickly. This effect can be obtained even if the viscoelastic vibration absorber is provided between the mass body 47 and the substrate 41 shown in the first embodiment.

Next, a third embodiment will be described with reference to FIG. Still another variable natural frequency type vibration control device 110 according to the present invention includes a mounting base 91, a guide shaft 95 vertically provided at the center of the mounting base 91, and a linear bearing 109 sliding on the guide shaft 95. A mass body 92 that is inserted as much as possible, a symmetrical cantilever-shaped leaf spring 100 that supports the mass body 92, and a mass body supporting point of the leaf spring 100 are moved to change the spring constant and be unique. A natural frequency changing means for changing the frequency is provided. The reason why the leaf springs that support the mass body are symmetrically provided in this manner is that a moment is not generated in the mounting portion. In addition, the spring constants of the leaf springs 100 which are bilaterally symmetrical are the same.

Further, the natural frequency varying means will be described. Leaf spring mounting portions 99 are erected on both left and right wings of the base 91, and each leaf spring mounting portion 99 is a cantilevered leaf spring 10.
The base end of 0 is fixed, and the free ends of both leaf springs 100 are in a state of facing each other toward the center.

On the other hand, a guide 101 extending in the left-right direction is provided on the lower surface of the mass body 92, and a pair of left and right nuts 102L, 10 are slidable along the guide 101.
2R is provided, and a roller 103 running on the leaf spring 100 is connected to each nut. Bearings 104 are provided on the lower surface of the mass body 92, and the left and right ends of the left and right screw shafts 105R and 105L are rotatably supported by the bearings 104. The left screw shaft 105L has the nut 102L, and the right screw shaft 105R has the nut 10L.
2R are screwed together, and gears 106L and 106R are fixed to the respective screw shafts. On the other hand, mass 9
An elastic adjusting motor (natural frequency varying means) 107
Is provided, and the pinions 108R, 108 fixed to the elasticity adjusting motor (natural frequency varying means) 107 are provided.
L meshes with the gears 106R and 106L, respectively.

Therefore, in the vibration control device 110 of variable natural frequency, the elastic adjusting motor (natural frequency varying means) is used.
When the screw shafts 105L and 105R are driven to rotate by the operation of 107, the nuts 102L and 102R and the rollers 103 are displaced in a direction in which they come into contact with and separate from each other, and thereby the elastic coefficient (spring constant) of the leaf spring 100 changes. It is like this.

[0029]

As described above, in the vibration control device of the natural frequency variable type according to the present invention, the springs for supporting the mass body are provided symmetrically with respect to the guide shaft to change the mounting angle of the mass body or the mass body. A cantilever-shaped leaf spring to be supported is provided symmetrically, and the natural frequency varying means for varying the natural frequency by changing the spring constant by moving the mass support point of the leaf spring is provided. As a result, the spring that supports the mass body prevents the moment from being generated in the mounting part.
Despite the fact that it is a vibration control device with a variable natural frequency that can respond to changes in the vibration frequency of general-purpose equipment such as industrial machines and construction machines that are vibrating objects, vibration control with a variable natural frequency The device design does not become complicated.

[Brief description of drawings]

FIG. 1 is a diagram showing a vibration control device of variable natural frequency according to the present invention.

FIG. 2 is a diagram showing another natural frequency variable type vibration control device embodying the present invention.

FIG. 3 is a diagram showing still another natural frequency variable type vibration control device embodying the present invention.

FIG. 4 is a diagram showing still another natural frequency variable type vibration control device embodying the present invention.

[Explanation of symbols]

 40 Variable Vibration Control Device for Natural Frequency 41 Mounting Base 46 Guide Shaft 47 Mass 55L, 55R Symmetrical 52 Natural Frequency Changing Means θ Angle K Spring Constant

Claims (3)

[Claims] 1. An actual vibration frequency of a vibrated object which is vibrated by an exciting force is measured, and vibration is absorbed by changing a natural frequency so that an anti-resonance point is formed near the vibration frequency. A natural frequency variable type vibration damping device for damping vibration by means of a mounting base, a guide shaft standing upright on the mounting base, and a mass body slidably mounted on the guide shaft. Bilateral symmetric spring means for supporting the mass body and eigenfrequency varying means for varying the natural frequency by displacing the mass body supporting point of the spring means symmetrically are provided. A natural frequency variable type vibration damping device characterized in that 2. An actual vibration frequency of an object to be vibrated which receives an exciting force is measured, and vibration is absorbed by changing a natural frequency so that an anti-resonance point is formed near the vibration frequency. A variable damping natural frequency type vibration damping device, comprising: a mounting base; a guide shaft vertically installed at the center of the mounting base; and a mass body slidably mounted on the guide shaft. , One end is attached to the mass body and the other end is attached to the mounting base side, and the spring symmetrical to the guide shaft supporting the mass body and the position of the other end of the symmetrical spring to the mounting base. A natural frequency variable means for moving the natural frequency of the spring to change the spring constant by changing the angle of the spring with respect to the mounting base symmetrically. Type vibration control device. 3. An actual vibration frequency of an object to be vibrated which receives an exciting force is measured, and vibration is absorbed by changing a natural frequency so that an anti-resonance point is formed near the vibration frequency. A variable natural frequency type vibration damping device that suppresses vibration by means of a mounting base, a guide shaft vertically installed on both end sides of the mounting base, and a slidable insertion common to the guide shaft. A mass body, a left-right symmetric cantilever-shaped leaf spring supporting the mass body, and a mass body supporting point of the leaf spring are moved symmetrically to change the spring constant to change the natural frequency. A natural frequency variable type vibration damping device comprising variable natural frequency varying means.