JPH11230851A - Exciter and method for measuring propagation speed of vibration wave - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the risk for moving an excitation position with a simple mechanical configuration by connecting an excitation generation part to a heavy weight via an excitation- prevention buffering device for absorbing the horizontal constituent of vibration. SOLUTION: An exciter consists of a vibration generator 1 and a heavy weight 2, and both of them are connected via a vibration-prevention buffering device 3. The vibration generator 1 is constituted of a rotary shaft 1a and an unbalanced mass body 1b, and the heavy weight 2 consists of a base part 2a and a plurality of disk-shaped weights 2b. Also, the vibration-prevention buffering device 3 consists of inner and outer shells made of aluminum, and the inner shell is connected to the vibration generator 1 and the outer shell is connected to the heavy weight 2, thus absorbing the horizontal constituent of vibration being generated in the vibration generator 1. In this case, the unbalanced mass body 1b is also rotated by the rotation of the rotary shaft 1b, and the generated vibration is transferred to the heavy weight 2 based on the reaction principle and is transferred to a target that is the installation location of a vibrator. The vibration has a horizontal constituent except a vertical direction since it is generated by a centrifugal force. The horizontal constituent is absorbed by the vibration-prevention buffering device 3, thus eliminating the risk for causing an excitation position from moving.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration exciter for applying vibration to an object, and more particularly to a vibration exciter suitable for use when the object is ground.

[0002]

2. Description of the Related Art Conventionally, when measuring physical properties such as allowable bearing capacity of the ground, vibration waves generated by applying vibration to the ground are detected by a vibration detector, and particularly, surface waves are detected. The allowable bearing capacity of the ground was determined by the propagation speed. A vibration exciter generally used in such a system is disclosed in
No. 24185, JP-A-55-106333, and the like.

[0003]

The former exciter described above has the following problems. That is, the exciter has a structure in which the reaction mass is magnetically suspended by the magnet provided with the electromagnetic coil on the support structure and vibrates. In order to vibrate the reaction mass itself, a strong magnet is required to drive the mass. In addition, since a large amount of electric power is required for driving, a large generator is required depending on the installation location.
Accordingly, a very large cost is required for the configuration of the exciter.

Further, in the latter exciter, horizontal vibration is generated due to the rotation of the mass body, which may cause the exciter to move from the initial installation location, that is, the exciter position. May move. Furthermore, these conventional exciters described above can generate only a narrow-band vibration, and cannot generate a wide-band vibration at a time.

An object of the present invention is to provide a vibration exciter which can remove vibrations with a simple mechanical structure and does not move its vibration generating position. Another object of the present invention is to provide a vibration exciter that can generate a broadband vibration at a time.

[0006]

According to a first aspect of the present invention, there is provided a vibration exciter, comprising: a vibration generating unit comprising a rotating shaft and an unbalanced mass provided on the rotating shaft; And a weight that transmits the vibration of the part to the object, wherein the vibration generating part and the weight are connected via a vibration isolator that absorbs a horizontal component of the vibration.

Here, the rotating shaft is a shaft that is rotated by the power of a motor, an engine, or the like. Further, the rotation cycle of the rotation shaft may be arbitrarily controlled. The unbalanced mass body is not particularly limited as long as it generates a vibrating force when rotated, and includes, for example, a mass body having a rotating shaft provided at an eccentric position. The unbalanced mass body may be integrated with the rotating shaft or connected separately. It is preferable that the vibrating force of the vibration generating section is variable so that a desired vibration can be generated. The excitation force can be changed, for example, by changing the rotation period of the rotating shaft, the mass of the unbalanced mass body, or the distance from the axis to the center of gravity of the unbalanced mass body.

The weight is relatively heavy in order to prevent the vibration generating portion from jumping as much as possible due to the vibration and to move the vibration generating position. The weight is preferably one that can be attached to and detached from the vibration generating section so that transportation, assembly and disassembly at the site are easy. For the same reason, it is preferable that the weight itself can be disassembled. The weight may have a container-like structure that can be filled with any substance such as a liquid or a solid.

The positional relationship between the vibration generator and the weight is not particularly limited. For example, the vibration generating section may be provided above the weight or may be provided below the weight.

The vibration damping device can absorb the horizontal component of the vibration, and its shape is not particularly limited. For example, a configuration in which an elastic body is inserted between the inner and outer shells having a displacement of 45 degrees, which is constituted by a square-shaped inner and outer shells and an elastic body, may be mentioned,
The anti-vibration shock absorbers are provided in the same absorption direction. Also,
The non-absorbing direction is set to the vertical direction or the like.

According to a second aspect of the present invention, there is provided a vibration exciter, comprising: a vibration generating unit including a rotating shaft and an unbalanced mass body provided on the rotating shaft; and a weight that transmits the vibration generated by the vibration generating unit to an object. The vibration exciter has a configuration in which a movement preventing device for preventing a vibration position from moving in the horizontal direction due to vibration of the vibration exciter is slidably attached to the vibration exciter body.

Here, the movement preventer prevents the exciter itself from moving in the horizontal direction when vibration is generated by the exciter. Further, the vibration exciter may vibrate in the vertical direction when the vibration is generated, so that the movement preventing device is slidable. The movement preventing device may be integral with or separate from the vibration exciter. In addition, it is preferable to provide a spike or to make the weight of the movement preventing device twice or more that of the exciter so that the device can be securely installed on the ground surface or the like.

According to a third aspect of the present invention, in the vibration exciter, a first vibration generating unit including a rotating shaft and a first unbalanced mass provided on the rotating shaft; and a rotation of the first unbalanced mass. A second vibration generator having a second unbalanced mass body that rotates with a different period and a weight that transmits the vibrations of the first and second vibration generators to the object.

Here, the first and second vibration generators may be configured to have different vibrating forces in advance, or may be capable of adjusting the vibrating force arbitrarily. Further, the drive source for the rotating shaft may be shared. It is preferable that the rotation axes of the first and second vibration generating units are parallel to each other in order to efficiently generate a vibrating force.

According to a fourth aspect of the present invention, there is provided the vibration exciter according to the first to third aspects.
The exciter according to any one of the preceding claims, wherein a spike is provided on a contact surface with the object.

Here, the spike is a protruding member that can penetrate an object such as the ground, and is used to prevent the vibration position from moving. The length of the spike may be appropriately set based on the vibrating force or the like.

According to a fifth aspect of the present invention, there is provided the vibration exciter according to the first to third aspects.
The exciter according to claim 1, wherein the weight has a dividable configuration.

Here, a plurality of members constituting the weight can be attached and detached so that the weight can be divided.

The vibration exciter according to the sixth aspect is characterized in that:
The exciter according to any one of the preceding claims, wherein a weight of the exciter is equal to or greater than an excitation force of the vibration generating unit.

Here, the excitation force can be obtained from the number of revolutions of the rotating shaft, the weight of the unbalanced mass body, the distance from the axis to the unbalanced mass body weight, and the like. Can be designed.

According to a seventh aspect of the present invention, there is provided a method for measuring the propagation speed of a vibration wave, wherein the ground is vibrated by using the vibration exciter according to any one of the first to sixth aspects, and the transmitted vibration wave is detected by a vibration detector. This is a method of calculating the propagation speed from.

Here, to calculate the propagation speed of the vibration wave, for example, a time difference Δt between the vibration waves detected by the two vibration detectors is obtained, and the distance between the vibration detectors is divided by the time difference Δt. You can ask. Alternatively, a fast Fourier transform (FFT) is performed, and 2
It can be obtained from the phase difference between the two vibration detectors.

[0023]

According to the vibration exciter of the first aspect, the unbalanced mass body is also rotated by the rotation of the rotating shaft, and vibration is generated. This vibration is transmitted to the weight by the principle of action and reaction, and then transmitted to the object where the vibration exciter is installed. Also, since the vibration is generated by the rotation of the unbalanced mass body,
Has a horizontal component. However, the horizontal component of the vibration is absorbed by the vibration isolator. That is, there is no fear that the vibration position moves.

With the vibration exciter according to the second aspect, the movement preventing device prevents the movement in the horizontal direction, so that there is no possibility that the vibration generating position moves laterally.

According to the vibration generator of the third aspect, since the rotation periods of the two unbalanced mass bodies are different, it is possible to simultaneously generate vibration excitation forces having different frequency bands. That is, a broadband vibration can be generated.

With the vibration exciter according to the fourth aspect, the spike can penetrate an object such as the ground, for example, so that it can be fixed even in an installation place where strong fixing is difficult.

The vibration exciter according to the fifth aspect facilitates transportation, assembling and disassembly on site.

With the vibration exciter according to the sixth aspect, jumping at the vibration generating position is substantially eliminated, and there is no possibility that the vibration generating position moves.

According to the vibration wave propagation velocity detecting method of the present invention, since the vibrating position does not move in the horizontal direction, for example, the relative position of the vibration detector with respect to the vibrating position does not change, and the propagation velocity is accurately calculated. be able to. In addition, since vibration in a wide band can be detected, vibration waves that propagate at various depths at once can be efficiently calculated.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] First, a first embodiment of a vibration exciter according to the present invention will be described. FIG. 1 is a partial cross-sectional perspective view of Embodiment 1 of the present invention. FIG. 2 shows a front view. The exciter shown in the figure comprises a vibration generator 1, a weight 2, and a vibration damping device 3. Further, the vibration generator 1 and the weight 2 are connected via a vibration damping device 3.

Next, the vibration generator will be described with reference to FIG. FIG. 3 is a partial cross-sectional top view of the vibration generator. The vibration generator 1 includes a rotating shaft 1a, an unbalanced mass body 1b provided on the rotating shaft 1a, and a motor 1c. The rotating shaft 1a is rotatably supported by bearings 1d and bearings 1e on both sides. An unbalanced mass body 1 including a fixed weight 1b1 and an adjustment weight 1b2 at both ends of the rotating shaft.
b is provided. The adjustment weight 1b2 is for changing the vibrating force, and several types having different masses are prepared. The vibrating force can be changed by appropriately changing this.

A motor 1c is provided at the center,
The rotary shaft 1a is driven. The output of this motor 1c is 400
W, and the number of rotations can be arbitrarily set from 0 to 180 rotations / second by inverter control. Further, the motor 1c and the bearing 1e are integrally attached to the housing 1f.

Next, the weight 2 will be described. The weight 2 includes a base 2a and a plurality of disk-shaped weights 2b, and a desired weight can be obtained by combining these weights. Here, the base 2 a is connected to the vibration generator 1 via the vibration damping device 3. Weight 2b is 1 for each
5 kg, and a side wall is provided with a portable handle 2c and a connecting member 2d for connection. Thus, the weight 2
By increasing or decreasing the weight of the exciter, it is possible to prevent the exciter from jumping or to jump on purpose,
It is easy to carry. Further, a spike 2e is protruded from the bottom surface of the weight so as to prevent the exciter from moving due to the vibration of the exciter.

Next, the vibration damping device will be described. 4A and 4B are explanatory views of the vibration damping device, wherein FIG. 4A is a perspective view and FIG. 4B is a front view. The vibration damping device 3 includes an outer shell 3a and an inner shell 3b made of aluminum, and a columnar rubber 3c. The outer shell 3a is provided with a space having a substantially rectangular cross section, into which the inner shell 3b having a substantially rectangular cross section is inserted by being displaced by 45 degrees. In addition, rubber 3
c is press-fitted. When a load in the twisting direction is applied to the outer shell 3a or the inner shell 3b, the rubber 3c is compressed while rolling between the inner and outer shells, and can absorb the horizontal component of the load. The inner shell 3 b is connected to the vibration generator 1, and the outer shell 3 a is connected to the weight 2 in such a direction as to absorb the horizontal component of the vibration. Therefore, the horizontal component of the vibration generated in the vibration generating section 1 is substantially absorbed by the vibration isolator.

In addition, there is a vibration damping device having a structure shown in FIG. Similarly, rubber is press-fitted at two places between the inner and outer shells so that the horizontal component of the load can be absorbed. In this case, a spring may be used instead of rubber.

The vibration generating portion, the vibration damping member, and the weight are configured to be substantially point-symmetric with respect to the center of gravity when viewed from above. The vibration exciter is configured such that a straight line passing through the center of gravity of the vibration isolating buffer member and the center of gravity of the weight intersects the rotation axis of the vibration generating unit. By configuring the vibration exciter in this way, it is made as stable as possible at the time of vibration generation. And since this exciter has a small number of members, it can be realized with a simple mechanical configuration.

Next, the operation will be described. Here, a description will be given of a case where the vibration exciter is mounted on the ground surface. Motor 1c
Is rotated, the rotation of the motor is transmitted to the rotating shaft 1a and the unbalanced mass body 1b. The vibrating force is generated by the rotation of the unbalanced mass body 1b. The excitation force F is F = m
rω ² (m: mass of the weight, r: distance from the axis to the center of gravity of the weight, ω: angular velocity). Since the vibrating force is generated by a so-called centrifugal force, it has a horizontal component other than in the vertical direction. The above-described vibration damping device 3 is provided in a direction in which the horizontal component can be absorbed. In addition, the vertical component of the vibrating force becomes a force in the opposite direction up and down, and vibrates the installation location of the vibrator according to the principle of action / reaction. For example, when the vertical component is facing upward, the installation location receives a vertical downward force via the weight.
In this manner, the horizontal component of the vibration is substantially absorbed, and the vertical vibration occurs on the ground. Further, the vibration exciter does not jump in the horizontal direction, and the displacement of the vibration generation position does not occur. Further, when the weight of the vibration exciter is equal to or more than the vibration force F, there is no possibility that the vibration exciter will jump.

[Second Embodiment] Next, a second embodiment of the vibration exciter according to the present invention will be described. FIG. 6 shows a second embodiment of the present invention. Here, (a) is a perspective view and (b)
Is a front view. In addition, description of portions common to those described above will be omitted. The vibration exciter of FIG. 6 includes a vibration generator 1, a weight 2, a vibration damping device 3, and a movement preventing device 4.

If the vibrating force is greater than the weight of the exciter, the exciter may jump and move during the exciter. That is, there is a possibility that the vibration position moves. Therefore, the movement preventers 4 are provided on both sides so as to surround the weight, so that the exciter does not move in the horizontal direction. However, the exciter body excluding the movement preventing device is slidable in the vertical direction. The movement preventing device 4 has twice the weight of the exciter excluding the movement preventing device so that it does not move even when a horizontal load is applied. further,
A spike 4a for penetrating into the ground is provided on the contact surface with the ground surface. Also, this vibration exciter can be realized with a simple mechanical configuration as in the first embodiment.

Third Embodiment Next, a third embodiment of the vibration exciter according to the present invention will be described. FIG. 7 shows a third embodiment of the present invention. Here, description of parts common to the above-described contents will be omitted. The vibration exciter of FIG. 7 includes first and second vibration generation units 1 and 1, a weight 2, a vibration damping device 3,
3 The rotation cycle of the first and second vibration generators 1 and 1 can be set arbitrarily. Further, as described above, the rotation shafts 1a and 1a intersect with the straight line passing through the center of gravity of the vibration generating portion and the weight. Furthermore, the two rotation shafts 1a, 1a are substantially parallel.

The oscillating force is proportional to the square of the mass and frequency of the unbalanced mass, as is evident from the above formula of F.
Therefore, for example, if it is attempted to generate all vibrations in the frequency band (5 to 150 Hz) necessary for analyzing the ground structure of a residential land with a single unbalanced mass body, the amplitude of the vibration wave is extremely small in a low frequency band, and conversely. In the high frequency band, it becomes extremely large. Therefore, if these vibration waves are to be detected, a large dynamic range is required for the vibration detector, which increases the cost.

Therefore, as in this embodiment, the vibration is generated by using the two vibration generators 1 and 1 at different rotational frequencies. At this time, since the vibration force is proportional to the square of the frequency, the masses of the weights 1b and 1b are also appropriately varied. Specifically, the heavier unbalanced mass in the first vibration generator is rotated at a lower frequency (20 Hz), and the lighter unbalanced mass in the second vibration generator is rotated at a higher frequency (90 Hz). Rotate. As a result, the band of the vibration wave of the first vibration generator is about 5 to 30 Hz, and the band of the vibration wave of the second vibration generator is about 30 to 120 Hz. Can generate a relatively flat vibration wave.
Also, this vibration exciter can be realized with a simple mechanical configuration as in the first embodiment.

FIG. 8 shows another vibrator in which the arrangement of the vibration generating section and the like is changed.

Fourth Embodiment Next, a description will be given of a method for measuring the propagation velocity of an oscillating wave according to a fourth embodiment of the present invention. 9A is a cross-sectional view of Embodiment 4 of the present invention, and FIG. 9B is a top view. Here, the above-mentioned exciter is used.

The vibration exciter 5 and the vibration detectors 6 and 6 are installed so as to be substantially perpendicular to the ground surface when viewed in a sectional view, and are installed so as to be on one straight line when viewed from the top. I have. The vibration detector 6, 6 are column set at intervals of a distance S _1.

Here, vibration is applied to the ground 7 by the exciter 5, and the transmitted vibration is detected by the vibration detectors 6, 6. The calculating unit 8 obtains a cross-correlation coefficient of the vibration waves detected by the two vibration detectors 6 by a fast Fourier transform (FFT), and calculates the cross-correlation coefficient by the phase difference Δt when the value becomes maximum. by dividing the distance S ₁ of calculating the propagation velocity of the vibration wave.

The number of vibration detectors is not particularly limited as long as it is two or more. The obtained propagation speed is used when estimating the ground structure. Further, since the vibration exciter 5 is of the above-described embodiment, no movement of the vibration generation position occurs. Therefore, since the interval between the vibration detectors does not change,
An accurate propagation speed can be obtained. Further, since vibrations in a wide band can be generated, vibrations of various frequencies can be detected at once. Therefore, it is possible to calculate the propagation speed of the vibration wave propagating at various depths.

[0048]

As described above, since the horizontal component of the vibration is absorbed by the vibration generator according to the first aspect, there is no possibility that the vibration position moves. Further, since the number of constituent members is small, it can be realized with a simple mechanical configuration.

According to the vibration exciter of the second aspect, since the movement preventing device prevents the horizontal movement of the vibration exciter, there is no possibility that the vibration generating position is moved. Further, since the number of constituent members is small, it can be realized with a simple mechanical configuration.

According to the vibration generator of the third aspect, a broadband vibration can be generated at a time. For example, when wide-band vibration is required, such as when estimating the ground structure of a residential land, it is not necessary to change the frequency of the vibration or the excitation force each time. Further, the man-hour required for measuring the vibration is reduced. Further, since the number of constituent members is small, it can be realized with a simple mechanical configuration.

According to the vibration exciter according to the fourth aspect, the vibration exciter can be fixed to the object, and there is no possibility that the excitation position is shifted.

The vibration exciter according to the fifth aspect facilitates transportation, assembling and disassembling on site.

With the vibration exciter according to the sixth aspect, jumping at the vibration generating position is substantially eliminated, and there is no possibility that the vibration generating position moves. .

According to the vibration wave propagation velocity detecting method of the present invention, the propagation velocity can be calculated accurately or efficiently.

[Brief description of the drawings]

FIG. 1 is a partial sectional perspective view showing a vibration exciter according to a first embodiment of the present invention.

FIG. 2 is a front view showing the vibration exciter according to the first embodiment of the present invention.

FIG. 3 is a partial cross-sectional top view illustrating a vibration generating unit of the vibration exciter according to the first embodiment.

FIG. 4 is an explanatory view showing a vibration damping device according to the present invention.

FIG. 5 is a front view showing another embodiment of the vibration damping device according to the present invention.

FIG. 6 is an explanatory diagram illustrating a vibration exciter according to a second embodiment of the present invention.

FIG. 7 is an explanatory diagram illustrating a vibration exciter according to a third embodiment of the present invention.

FIG. 8 is an explanatory diagram showing another form of the vibration exciter according to the third embodiment.

FIG. 9 is an explanatory diagram showing a method of measuring a propagation speed of an oscillating wave according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vibration generating part 1a Rotating shaft 1b Unbalanced mass body 1c Motor 1d Bearing 1e Bearing 1f Housing 2 Weight 2a Base 2b Weight 2c Handle 2d Connecting member 2e Spike 3 Vibration damping device 3a Outer shell 3b Inner shell 3c Rubber 4 Move prevention Tool 4a Spike 5 Exciter 6 Vibration detector 7 Ground

Claims (7)

[Claims] 1. A vibration exciter comprising: a vibration generating unit including a rotating shaft and an unbalanced mass body provided on the rotating shaft; and a weight transmitting the vibration generated by the vibration generating unit to an object. A vibration exciter characterized in that the vibration generator and the weight are connected via a vibration damping device that absorbs a horizontal component of the vibration. 2. A vibration exciter comprising: a vibration generating unit including a rotating shaft and an unbalanced mass provided on the rotating shaft; and a weight transmitting the vibration generated by the vibration generating unit to an object. A vibration exciter characterized in that a movement preventing device for preventing the vibration position from moving in the horizontal direction due to vibration of the vibration exciter is slidably attached to the vibration exciter body. 3. A first vibration generating section comprising a rotating shaft and a first unbalanced mass provided on the rotating shaft, and a second vibration rotating portion having a rotation cycle different from that of the first unbalanced mass. A vibration exciter comprising: a second vibration generating unit having the unbalanced mass body described above; and a weight transmitting the vibration by the first and second vibration generating units to the object. 4. The vibration exciter according to claim 1, wherein a spike is provided on a contact surface with the object. 5. A vibration exciter according to claim 1, wherein said weight is dividable. 6. The vibration exciter according to claim 1, wherein a weight of the vibration exciter is equal to or more than a vibration generating force of the vibration generating unit. 7. A vibration, wherein the ground is vibrated by using the vibration exciter according to claim 1, a propagated vibration wave is detected by a vibration detector, and a propagation velocity is calculated from the vibration wave. Wave propagation velocity measurement method.