JP3721664B2 - Rotating epicenter device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rotary seismic source device that is installed on the ground and continuously generates weak vibrations corresponding to seismic waves for the purpose of exploring geological structures.
[0002]
[Problems to be solved by the invention]
Conventionally, in geological structure exploration systems that explore the geological structure by observing the propagation of artificially generated seismic waves, dynamite and other explosives are exploding in the ground as a method for generating artificial earthquakes. May generate seismic waves. However, the method using explosives is not suitable for a system that continuously monitors changes in a wide range of geological structures over a long period of time because the obtained seismic wave is a single pulse-like vibration. Therefore, as a method for generating seismic waves continuously, a method for generating weak seismic waves continuously by mechanically reciprocating a weight using hydraulic pressure, pneumatic pressure or electromagnetic force has been proposed. However, even with these mechanical vibration generation methods, although continuous seismic waves can be obtained, the vibration force and frequency can be arbitrarily set and the vibration cannot be reproduced continuously with high accuracy. In addition, when mechanical vibration is generated, there is a problem that noise can be generated, so that a place where it can be installed is limited to a place away from a house.
[0003]
[Means for Solving the Problems]
In order to solve the above problems, the invention of claim 1 embeds the main body in the ground, supports the eccentric rotor in the inner hollow portion formed in the main body, and connects the servo motor to the eccentric rotor. Drives at the set rotation speed. Thereby, it is possible to continuously generate seismic waves having an arbitrary frequency.
[0004]
Further, in the invention of claim 1, the eccentric rotor is constituted by two or more eccentric weights divided in the axial direction, and each of the eccentric rotors is connected through the rotation shaft common to the rotation center portion of each eccentric weight, By supporting both ends of each eccentric shaft in the axial direction via the bearings, it is possible to adjust the strength of the generated vibration depending on the number of eccentric weights attached and the mass of the eccentric weight. The generated excitation force is transmitted to the main body via each bearing.
[0005]
Further, in the first aspect of the present invention, the eccentric weight is axially positioned by sandwiching the buffer plate made of an elastic material between the eccentric weights, so that the eccentric weight is displaced in the axial direction. Even if it occurs, it is prevented from being absorbed by the buffer plate and interfering with other eccentric weights .
[0006]
According to a second aspect of the present invention, in the first aspect of the present invention , the eccentric weight and the rotary shaft are connected by forming a key groove in the fitting portion between each eccentric weight and the rotary shaft and fitting the key. The shaft hole of each eccentric weight is made larger than the rotation axis, and each eccentric weight can be moved relative to the rotation axis in the key height direction. Although it is below the range, it becomes free in the radial direction, and the load on the rotating shaft is reduced .
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a longitudinal sectional view showing an internal structure of an embodiment of the present invention, and FIG. 2 is a transverse sectional view of a main part of FIG. In FIG. 1, reference numeral 1 denotes a rotating shaft, and an upper end is connected to an output shaft 4 of a servo motor 3 via a coupling 2. In order to improve the assembly workability, the rotary shaft 1 has a large lower portion and a small upper portion, and an eccentric weight 5 is fitted to the lower large diameter portion and an eccentric weight 6 is fitted to the upper small diameter portion. ing. The eccentric weights 5 and 6 have a cylindrical shape as a whole, bearing fitting portions are formed on the peripheral surfaces of the upper and lower ends, and one side surface of a portion between the upper and lower bearing fitting portions is excised and eccentric. Part 5b is formed. The eccentric weight 5 is supported by a casing 9 serving as a main body through upper and lower bearing fitting portions via bearings 7 and 8. Similarly, the eccentric weight 6 has upper and lower bearing fitting portions supported by the casing 9 via bearings 11 and 12.
[0008]
Further, as shown in FIG. 2, the eccentric weight 5 is formed with a shaft hole slightly larger than the rotating shaft 1 at the center portion to be fitted with the rotating shaft 1, and further the eccentricity of the rotating shaft 1 and the eccentric weight 5. Key grooves 1a and 5a are formed at positions opposite to the portion 5b, respectively, one surface of the key 13 is press-fitted and fixed in the key groove 1a of the rotary shaft 1, and the other surface of the key 13 is slid in the height direction in the key groove 5a. It is movably fitted. In this state, when the rotary shaft 1 is driven to rotate, the eccentric weight 5 is rotated via the key 13.
Here, if the mass of the eccentric portion 5b of the eccentric weight 5 is m, the rotation radius of the mass m is r, and the rotation angular velocity is ω, the excitation force F shown in the following equation is generated in the eccentric weight 5.
[0009]
[Expression 1]
F = m · r · ω ²
[0010]
Thus, the excitation force F generated in the eccentric weight 5 by being rotationally driven is transmitted to the casing 9 through the bearings 7 and 8. At this time, although the eccentric weight 5 is supported by the bearings 7 and 8, the eccentric weight 5 tends to narrow the height dimension of the key groove 5a due to the entire elastic deformation caused by the mounting gap and the excitation force F. Moved. Therefore, the clearance between the rotary shaft 1 and the shaft hole of the eccentric weight 5 is set to be larger than the maximum value of the displacement generated in the eccentric weight 5 in advance. As a result, even when the eccentric weight 5 is displaced from the central axis due to the excitation force corresponding to the rotational speed, the displacement is not transmitted to the rotary shaft 1.
[0011]
That is, although the rotating shaft 1 rotates the eccentric weight 5 to generate an exciting force, all the exciting force is transmitted to the casing 9 via the bearings 7 and 8, so that the rotating shaft 1 is moved to the eccentric weight. No radial force or bending load is received from 5. The rotary shaft 1 and the eccentric weight 6 are also connected by the same key structure, and the excitation force generated by the rotation of the eccentric weight 6 is not transmitted to the rotary shaft 1 at all, and the bearings 11 and 12 are connected. To the casing 9. As a result, in the casing 9, the same-phase excitation forces transmitted from the eccentric weights 5 and 6 are added to generate a larger vibration, which is propagated as a seismic wave to the surrounding ground.
[0012]
In FIG. 1, a rubber packing 14 serving as a buffer plate is sandwiched and supported between the eccentric weight 5 and the eccentric weight 6. This is incorporated in order to position the eccentric weight 6 in the axial direction with respect to the eccentric weight 5 when the eccentric weight 5 and the eccentric weight 6 are inserted into the rotating shaft 1 and assembled. The thickness of the rubber packing 14 is a value calculated from the dimensions between the inner side surfaces of the pressing plates 15 and 16 incorporated in the upper and lower ends of the rotary shaft 1 and the axial dimensions of the eccentric weight 5 and the eccentric weight 6. At the time of stopping, that is, during assembly, the eccentric weight 5 and the eccentric weight 6 are supported without gaps in the axial direction.
[0013]
However, during operation, an excitation force is generated in the eccentric weight 5 and the eccentric weight 6 and these are transmitted to the casing 9 via the bearings 7 and 8 and the bearings 11 and 12. Since the eccentric weight 5 and the eccentric weight 6 have different axial lengths, the eccentric mass differs and the generated excitation force differs. Also, the allowable loads of the bearings 7 and 8 and the bearings 11 and 12 are different from each other, and further, an axial component of an exciting force is generated in each part due to a difference in rigidity of each part of the ground in contact with the casing 9. is there. As a result, displacement in a direction that interferes with each other may occur between the eccentric weight 5 and the eccentric weight 6 that are originally held in a separated state.
[0014]
For this reason, an unexpected stress is generated in the interference portion due to the displacement, and adversely affects the strength of each portion. However, in the embodiment of the present invention, since the rubber packing 14 is sandwiched between the eccentric weight 5 and the eccentric weight 6, the displacement in the direction of interfering with each other between the eccentric weight 5 and the eccentric weight 6 is caused. Even if it occurs, the rubber packing 14 is elastically deformed to absorb the displacement. As a result, it is not necessary to design the eccentric weight 5, the eccentric weight 6 and the portions that support them in consideration of these unexpected axial stresses.
[0015]
In FIG. 1, 17-19 are spacers for positioning the bearings in the axial direction, 20 is a coupling case for fixing the servo motor 3 to the casing 9, and 21 is an oil supply hole. Although not shown, an oil supply hose or pipe is connected to the oil supply hole 21 so that lubricating oil can be pumped from the ground to the inside.
Although not shown, an inverter is connected to the servo motor 3, and the rotational speed is precisely controlled according to the frequency of the necessary seismic wave.
Furthermore, in this embodiment, the two eccentric weights 5 and 6 are attached to the rotary shaft 1, but it is also possible to attach three or more eccentric weights.
[0016]
Furthermore, it is also possible to use a spline joint having a large radial gap between the shaft and the bearing portion for connecting the rotating shaft 1 and the eccentric weights 5 and 6.
Further, in this embodiment, as shown in FIG. 1, the rotary shaft 1 is set in the vertical direction and the main body is embedded in the ground. However, in addition to this installation mode, the rotary shaft 1 is set in the horizontal direction. It can be buried underground. In that case, one side surface of the casing 9 is buried in the ground so that it is close to the ground surface, and the servo motor 3 and the coupling case 20 are exposed without being buried. Specifically, a groove or the like is formed on the ground at the installation position, and the servo motor 3 and the coupling case 20 are exposed in the groove so that only a portion of the casing 9 is embedded in the ground. To do.
[0017]
【The invention's effect】
As described above, according to the rotary seismic source device of the present invention, the main body is embedded in the ground, and the eccentric rotor is pivotally supported in the inner hollow portion formed in the main body, and the servo motor is connected to the eccentric rotor. It is possible to continuously generate seismic waves having an arbitrary frequency by rotationally driving at the rotation speed thus set. As a result, when the rotary seismic source device of the present invention is used in a system that continuously monitors changes in geological structure for a long period of time, the excitation force and frequency set for the seismic wave are maintained with high accuracy and continuously. Therefore, the observation accuracy of the system can be dramatically improved. In particular, since this apparatus does not use fluid pressure or electromagnetic force, it hardly generates noise, so that it can be installed and used near a house.
[0018]
In addition, the eccentric rotor is constituted by two or more eccentric weights divided in the axial direction, and each of the eccentric weights is connected to each other through a rotation shaft common to the rotation center portion of each eccentric weight. By supporting the main body via the bearings, it is possible to adjust the strength of the generated vibration depending on the number of eccentric weights attached and the mass of the eccentric weight. In addition, the load applied to the rotating shaft is reduced by transmitting the excitation force generated by each eccentric weight to the main body via the respective bearings.
[0019]
Furthermore, each eccentric weight and the rotation shaft are connected by forming a key groove in the fitting portion between each eccentric weight and the rotation shaft and fitting the key, and the shaft hole of each eccentric weight is connected to the rotation shaft. Also, the eccentric weight can be moved relative to the rotation axis in the height direction of the key. As a result, the rotating shaft and each eccentric weight are free in the radial direction, although within a certain range, and the load on the rotating shaft is reduced.
[0020]
In addition, the shock absorber plate made of an elastic material is sandwiched between the eccentric weights so that the eccentric weight is positioned in the axial direction, so that even if an axial displacement occurs in each eccentric weight, the shock absorber plate Is prevented from interfering with other eccentric weights, and the operational stability is improved.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing an internal structure of an embodiment of the present invention.
2 is a cross-sectional view of the main part of FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Rotating shaft 1a Key groove 2 Coupling 3 Servo motor 4 Output shaft 5 Eccentric weight 5a Key groove 5b Eccentric part 6 Eccentric weight 7, 8 Bearing 9 Casing 11, 12 Bearing 13 Key 14 Rubber packing 15, 16 Holding plates 17-19 Spacer 20 Coupling case 21 Oil supply hole

Claims (2)

An eccentric rotor, a main body that pivotally supports the eccentric rotor in the inner hollow portion and embedded in the ground, and a servo motor that is connected to the eccentric rotor and rotationally drives the eccentric rotor at a set rotational speed ,
The eccentric rotor is composed of two or more eccentric weights divided in the axial direction, and each of the eccentric shafts is connected to each other through a rotation shaft common to the rotation center of each eccentric weight. Through the body,
A rotary seismic source device characterized by having an assembly structure in which a buffer plate made of an elastic material is sandwiched between the eccentric weights to position the eccentric weight in the axial direction . The rotary source device according to claim 1,
A key groove is formed in the fitting part between each eccentric weight and the rotation shaft, and the key is fitted to connect each eccentric weight and the rotation shaft. The shaft hole of each eccentric weight has a larger diameter than the rotation shaft. Thus, the rotary hypocenter device characterized in that each eccentric weight is movable relative to the rotation axis in the key height direction .

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