Pendulum type vibration isolation device

Abstract

To provide a pendulum type vibration control device which achieves high performance for damping rotational motion around a Z axis and suppressing a large amplitude when large force is applied.SOLUTION: A pendulum type vibration control device includes: a pendulum which hangs a vibration control object; and a damping mechanism which damps vibration of the pendulum. The pendulum includes: a handing material support substrate part; a hanging material hung from the hanging material support substrate part; and a vibration control object support substrate part which is hung by the hanging material and supports the vibration control object. The damping mechanism includes: a damping case provided at the vibration control object support substrate part, having a cylindrical outer shape, and including a viscous fluid housing part which houses viscous fluid serving as a damping material; and a damping application member in which one end side is directly or indirectly fixed to the handing material support substrate part, the other end side is immersed in the viscous fluid, and at least a part of a portion immersed in the viscous fluid is formed as a plurality of fins symmetrically protruding from a shaft center in an outer peripheral direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pendulum type vibration isolation device used for a surveillance television camera mounted on a pole on a highway or the like. [Background technology]

[0002] Pillars on which surveillance television cameras are mounted on highways are subject to large vibrations caused by passing vehicles, which could impair the quality of the camera images.

[0003] For this reason, various vibration isolation devices have been proposed to suppress vibration. For example, one device is disclosed that is applied to the support pillars of television cameras used to monitor highways, and has a pendulum rod with a weight attached to the bottom end, suspended via a universal joint, that oscillates in all horizontal directions. A rubber-like elastic body is applied with an initial compressive force to the outer periphery of the pendulum rod, thereby adjusting the frequency of the pendulum rod and attenuating the vibration.

[0004] Furthermore, for example, the disclosed pendulum comprises a hanger support base portion, a hanger suspended from the hanger support base portion, and a vibration-damping object support base portion that is suspended by the hanger and supports the vibration-damping object, and the damping mechanism comprises a viscous fluid tank that is provided in the vibration-damping object support base portion and is filled with a viscous fluid that serves as a damping material, and a spring body that has one end fixed to the hanger support base portion and the other end abutting against the bottom of the viscous fluid tank. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 7-243473 [Patent Document 2] Japanese Patent Publication No. 2022-035739 Summary of the Invention [Problem to be solved by the invention]

[0006] With the conventional technology described above, increasing the length of the pendulum can lower the natural frequency and improve the vibration isolation effect, but adding a damping mechanism to this has the problem that the natural frequency quickly becomes higher. Also, there are various natural frequency peaks at each site, and there is a problem that the natural frequency peak at each site may overlap with the resonance point of the damping mechanism, worsening the vibration.

[0007] Furthermore, even when the damping mechanism is configured to include a viscous fluid tank filled with a viscous fluid, which is a damping material, provided on the support base of the object to be vibration-damped, and a spring body with one end fixed to the support base of the hanger and the other end abutting the bottom of the viscous fluid tank, there are problems such as the performance not being sufficient in terms of, for example, the damping force against rotational movement around the Z axis, or the suppression of large amplitudes when a large force is applied, such as during an earthquake or a vehicle collision due to an accident.

[0008] The present invention has been made to solve the above-mentioned problems of the conventional art, and its object is to provide a pendulum-type vibration isolation device that has high damping performance for rotational motion around the Z axis and high performance for suppressing large amplitudes when a large force is applied. Another object of the present invention is to provide a pendulum-type vibration isolation device that can easily adjust vibration (resonance frequency). [Means for solving the problem]

[0009] The pendulum type vibration isolation device of the present invention is a pendulum type vibration isolation device comprising a pendulum suspending an object to be vibration-isolated and a damping mechanism for damping the vibration of the pendulum, wherein the pendulum comprises a hanger support base portion, a hanger suspended from the hanger support base portion, and an object to be vibration-isolated support base portion suspended by the hanger and supporting the object to be vibration-isolated, and the damping mechanism comprises a damping case provided on the object to be vibration-isolated support base portion and having a cylindrical outer shape and including a viscous fluid containing portion for containing a viscous fluid that is a damping material, and a damping member having one end fixed directly or indirectly to the hanger support base portion and the other end immersed in the viscous fluid, at least a portion of the portion immersed in the viscous fluid as a plurality of fins that protrude symmetrically from the axial center toward the periphery. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a pendulum type vibration isolator that has high damping performance for rotational movement around the Z axis and high performance for suppressing large amplitude when a large force is applied. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a perspective view schematically showing the overall configuration of a pendulum type vibration isolation device according to an embodiment; [Figure 2] FIG. 2 is a vertical cross-sectional view showing the configuration of a damping mechanism of the pendulum type vibration isolator of FIG. [Figure 3] 3A and 3B are diagrams showing the configuration of the damping case of the damping mechanism of FIG. 2, in which (A) is a top view and (B) is a side view. [Figure 4] FIG. 3 is a perspective view schematically showing the configuration of a cross-shaped fin of the damping mechanism of FIG. 2. [Figure 5] FIG. 2 is a diagram for explaining the installation state of the pendulum type vibration isolation device of FIG. 1. [Figure 6] 6 is a graph showing the vibration spectrum in the X direction of traffic vibration transmitted to the support pillar on which the pendulum-type vibration isolation device shown in FIG. 5 is installed. [Figure 7] FIG. 10 is a diagram for explaining a method for measuring the transmissibility of vibration. [Figure 8] 1 is a graph showing the relationship between vibration frequency and transfer function. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, a pendulum type vibration isolator according to an embodiment will be described with reference to the drawings. In each drawing, corresponding parts are given the same reference numerals and duplicated explanations will be omitted.

[0013] The pendulum-type vibration isolation device of this embodiment is a pendulum-type vibration isolation device consisting of a pendulum in which the object to be isolated (in this case, a television camera for monitoring roads) and an added mass are suspended by a hanging member, and a damping mechanism that damps the vibration of the pendulum.By adjusting the length of the pendulum, the natural frequency can be kept low while providing damping, making it possible to quickly converge residual vibrations.

[0014] As shown in Figure 1, a pendulum-type vibration isolation device 10 includes a hanger support base part 13, and multiple (for example, three) hangers 12 that make up the pendulum are suspended from this hanger support base part 13. The hanger 12 is not particularly limited, and for example, a wire, a chain, a rod, or the like can be used. In either case of the hanger 12, the connection part at the upper end to the hanger support base part 13 is connected by a connecting mechanism such as a pin or universal joint in a state that allows pendulum motion.

[0015] On the other hand, a support base plate 14 for the object to be vibration-damped is connected to the lower end of the hanging material 12. The connection portion with this support base plate 14 for the object to be vibration-damped is also connected by a connecting mechanism such as a pin or universal joint in a state in which pendulum motion is possible. An object to be vibration-damped (here, a television camera for monitoring roads) 11 is attached to the underside of the support base plate 14 for the object to be vibration-damped.

[0016] A damping mechanism 20 is provided between the hanger support base 13 and the vibration-isolating object support base 14. As shown in FIG. 2, the damping mechanism 20 has a cylindrical container-shaped damping case 21 provided on the vibration-isolating object support base 14. A viscous fluid tank 23 filled with a gel-like viscous fluid 22, which serves as a damping material, is formed on the bottom side of the damping case 21. As shown in FIG. 3(A), the viscous fluid tank 23 is composed of a groove-like recess that has a cross-like shape when viewed from above. In FIG. 3, (A) is a top view of the damping case 21, and (B) is a side view of the damping case 21, and in (B), the internal structure of the damping case 21 is indicated by dotted lines.

[0017] The lower end of a cross-shaped fin 25, which serves as a damping member and is suspended from the hanger support base 13 via a rod 24, is immersed in the viscous fluid tank 23. The width of the viscous fluid tank 23, which is made up of a cross-shaped groove, is configured to be wider than the thickness of the cross-shaped fin 25. The cross-shaped fin 25 is allowed to move and rotate within this cross-shaped groove, thereby damping vibrations. Furthermore, during large displacements, deformation of the viscous fluid 22 between the cross-shaped fin 25 and the sidewalls of the cross-shaped groove is suppressed, thereby suppressing large displacements.

[0018] In this embodiment, as shown in FIG. 4, cross-shaped fins 25 are used as the damping members. Each cross-shaped fin 25 is made up of four fins symmetrically projecting from the axial center toward the periphery at 90-degree intervals. However, this is not limiting. It is also possible to use a damping member made up of multiple fins symmetrically projecting from the axial center toward the periphery. For example, various types of damping members can be used, such as a damping member made up of three fins symmetrically projecting from the axial center toward the periphery at 120-degree intervals, or a damping member made up of six fins symmetrically projecting from the axial center toward the periphery at 60-degree intervals. If a damping member other than the cross-shaped fins 25 is used, the shape of the grooves provided in the viscous fluid tank 23 must also be changed.

[0019] The side walls of the cross-shaped grooves can be made of a hard material such as metal or resin. The width of the viscous fluid tank 23 made of cross-shaped grooves may be changed for each groove perpendicular to the X and Y directions. That is, depending on the vibration conditions at the installation location, the width of the groove in the X direction can be adjusted to be smaller or larger than the width of the groove in the Y direction, so that appropriate vibration damping can be achieved.

[0020] As described above, in this embodiment, the shape of the viscous fluid tank 23 is configured with cross-shaped grooves to match the shape of the cross-shaped fins 25. However, the shape of the viscous fluid tank 23 does not necessarily have to be cross-shaped, and the viscous fluid tank 23 may remain in the cylindrical shape of the damping case 21. This can be adjusted depending on the required damping force and the performance required to suppress large amplitudes during large displacements. Furthermore, the width of the cross-shaped grooves relative to the shape of the cross-shaped fins 25 can also be adjusted depending on the required damping force and the performance required to suppress large amplitudes during large displacements.

[0021] In this embodiment, the height position of the cross-shaped fins 25 can be adjusted at the attachment portion between the rods 24 and the cross-shaped fins 25, and the immersion depth of the cross-shaped fins 25 in the viscous fluid 22 can be adjusted. This makes it possible to adjust the magnitude of the damping force generated by the cross-shaped fins 25 to some extent, and to easily adjust the resonance frequency.

[0022] 2, a cushion 26 is disposed within the damping case 21 so as to surround the periphery of the cross-shaped fin 25. Meanwhile, a disc-shaped stopper plate 27 is disposed on the upper surface of the damping case 21, leaving a gap therebetween, and the cushion 26 is disposed between the damping case 21 and the stopper plate 27. The cushion 26 is formed, for example, from a low-resilience cushion made of low-resilience urethane foam or the like, has an uneven structure on one side, and is rolled into a cylindrical shape with the uneven surface facing inward. More specifically, for example, a urethane foam with an impact resilience modulus of 15% or less can be suitably used as the cushion 26.

[0023] In this embodiment, a gel-like viscous fluid 22 is used as the damping material, but a liquid one can also be used. However, since a liquid damping material may leak, it is preferable to use a gel-like viscous fluid 22. More specifically, for example, a silicone gel or the like can be suitably used as the gel-like viscous fluid 22.

[0024] In the pendulum type vibration isolation device 10 of this embodiment configured as described above, a damping force against vibration is generated by the components provided in the damping case 21, such as the viscous fluid 22, viscous fluid tank 23, and cross-shaped fins 25, as well as the cushion 26 and stopper plate 27. Of these, the viscous fluid 22, viscous fluid tank 23, and cross-shaped fins 25 act primarily against rotational and horizontal displacement. The cushion 26 and stopper plate 27 act primarily against vertical displacement, suppressing this and absorbing impact when large displacement occurs. The cushion 26 also suppresses large horizontal displacement and absorbs impact.

[0025] As shown in Fig. 5, the pendulum type vibration isolation device 10 configured as described above is attached to a support 30 provided on the shoulder of a highway 31 or the like, and is designed to isolate an object 11 to be isolated (here, a television camera for monitoring the road). In this case, the vibrations applied to the pendulum type vibration isolation device 10 from the support 30 can be divided into components in the direction of vehicle traffic on the highway 31 (Y direction), a direction perpendicular to the direction of vehicle traffic on the highway 31 (X direction), and a vertical direction (Z direction), as shown in Fig. 5. Of these, the vibration that particularly needs to be isolated is the X direction component.

[0026] Fig. 6 shows a graph of the vibration spectrum in the X direction of traffic vibration transmitted to the support pillar 30 as described above. In Fig. 6, the vertical axis represents vibration acceleration (dB) and the horizontal axis represents frequency (Hz). The peak on the left side of Fig. 6 is the resonance point of the road vibration in the elevated or bridge section, and the peak on the right side is the resonance point of the vibration of the support pillar 30. This traffic vibration shows the result of measuring vibration with the sensor 40 shown in Fig. 5, and represents the vibration before it is isolated by the pendulum type vibration isolation device 10. In this embodiment, the pendulum type vibration isolation device 10 is set to have a sufficient vibration isolation effect by adjusting its natural frequency to be between the above two peaks.

[0027] Next, an example of comparing transfer functions based on damping performance will be described. In this case, as shown in FIG. 7, sensor 40 measures vibration before vibration isolation by the pendulum-type vibration isolation device 10, and sensor 41 measures vibration after vibration isolation by the pendulum-type vibration isolation device 10. The vibration transmissibility is calculated from the ratio (measurement value of sensor 41 / measurement value of sensor 40). The results are shown in FIG. 8. In FIG. 8, the vertical axis represents the transfer function (dB) and the horizontal axis represents frequency (Hz). The dotted line represents the actual measurement results, and the solid line represents the predicted value when the damping rate of the pendulum-type vibration isolation device 10 is adjusted (reduced). As shown in FIG. 8, adjusting the damping rate of the pendulum-type vibration isolation device 10 can reduce the transfer function on average, and can particularly attenuate vibration at the peak of the resonance point of traffic vibration shown in FIG. 6.

[0028] Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0029] 10 Pendulum type vibration isolation device 11. Vibration isolation object 12 Hanging material 13 Hanger support base 14. Vibration isolation object support substrate 20 Damping mechanism 21 Attenuation Case 22 Viscous fluid 23 Viscous fluid tank 24 Bar material 25 cross fin 26 cushions 27 Stopper plate 30 pillars 31 Expressway 40,41 Sensor

Claims

1. A pendulum-type vibration isolation device comprising a pendulum from which an object to be vibration-isolated is suspended and a damping mechanism for damping the vibration of the pendulum, The pendulum is a hanger support substrate portion; a hanger suspended from the hanger support substrate portion; a vibration-damping object support substrate portion that is suspended by the suspension material and supports the vibration-damping object, The damping mechanism includes: a damping case provided on the vibration-isolating object support substrate portion, having a cylindrical outer shape, and including a viscous fluid containing portion for containing a viscous fluid as a damping material; a damping member having one end fixed directly or indirectly to the hanger support base portion and the other end immersed in the viscous fluid, at least a portion of the portion immersed in the viscous fluid being a plurality of fins that protrude symmetrically from the axial center toward the outer periphery; Equipped with A pendulum type vibration isolation device characterized by:

2. 2. The pendulum type vibration isolation device according to claim 1, the plurality of fins are cross-shaped fins; The viscous fluid storage portion is formed of a groove portion arranged in a cross shape on the lower side of the inside of the damping case, and the width of the cross-shaped groove portion is wider than the plate thickness of the cross-shaped fin. A pendulum type vibration isolation device characterized by:

3. 3. The pendulum type vibration isolation device according to claim 2, The damping member is movable up and down, and the immersion depth in the viscous fluid is adjustable. A pendulum type vibration isolation device characterized by:

4. 4. The pendulum type vibration isolation device according to claim 1, a stopper plate covering the upper surface of the damping case with a gap therebetween; a cushioning material interposed between the damping case and the stopper plate; Equipped with A pendulum type vibration isolation device characterized by:

5. 5. The pendulum type vibration isolation device according to claim 4, The cushion material is disposed in an annular shape along the inner side surface of the damping case, and has an uneven surface on the inside. A pendulum type vibration isolation device characterized by:

6. 5. The pendulum type vibration isolation device according to claim 4, The object to be isolated is a surveillance television camera for photographing vehicles passing by on a road. A pendulum type vibration isolation device characterized by:

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