Pendulum type vibration control 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 for use in 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 expressways 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 disclosed device is applied to the support pillars of television cameras used for monitoring highways, and has a pendulum rod with a weight attached to the lower end and suspended via a universal joint, which vibrates in all horizontal directions. A rubber-like elastic body is abutted against the outer periphery of the pendulum rod with an initial compression force, thereby adjusting the frequency of the pendulum rod and attenuating the vibration.

[0004] Also, for example, the pendulum includes a hanging material support base portion, a hanging material suspended from the hanging material support base portion, and a vibration-proof object support base portion that is suspended by the hanging material and supports the vibration-proof object, and the damping mechanism includes a viscous fluid tank provided in the vibration-proof object support base portion and filled with a viscous fluid that is a damping material, and a spring body having one end fixed to the hanging material support base portion and the other end abutted 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] JP 2022-035739 A Summary of the Invention [Problem to be solved by the invention]

[0006] In the conventional technology described above, the natural frequency can be lowered by increasing the length of the pendulum to improve the vibration isolation effect, but adding a damping mechanism to this leads to a problem that the natural frequency quickly becomes high. In addition, there are various natural frequency peaks at the site, and there is also a problem that the natural frequency peak at the 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 as a damping material and provided on the support base of the object to be vibration-proofed, and a spring body having one end fixed to the support base of the hanging material and the other end abutted against the bottom of the viscous fluid tank, there was still a problem that the performance was not sufficient, for example, in terms of the damping force against rotational motion around the Z axis, or in terms of suppressing 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 in the conventional art, and its object is to provide a pendulum type vibration isolation device that has high performance in damping rotational motion around the Z axis and suppressing large amplitude 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, the pendulum comprising a hanging material support base part, a hanging material suspended from the hanging material support base part, and an object to be vibration-isolated support base part suspended by the hanging material and supporting the object to be vibration-isolated, the damping mechanism comprising a damping case provided on the object to be vibration-isolated support base part and having a cylindrical outer shape and a viscous fluid containing part for containing a viscous fluid as a damping material, and a damping member having one end fixed directly or indirectly to the hanging material support base part and the other end immersed in the viscous fluid, at least a part of the part immersed in the viscous fluid being a plurality of fins protruding symmetrically from the axial center toward the periphery. Effect of the Invention

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

[0011] [Figure 1] 1 is a perspective view showing a schematic overall configuration of a pendulum type vibration isolation device according to an embodiment; [Diagram 2] 2 is a vertical cross-sectional view showing the configuration of a damping mechanism of the pendulum type vibration isolator of FIG. 1. [Diagram 3] 3A and 3B are diagrams showing the configuration of a damping case of the damping mechanism in FIG. 2, in which (A) is a top view and (B) is a side view. [Figure 4] FIG. 3 is a perspective view showing a schematic configuration of a cross-shaped fin of the damping mechanism shown in FIG. 2. [Diagram 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 in FIG. 5 is installed. [Figure 7] 1 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 PREFERRED EMBODIMENTS

[0012] Hereinafter, a pendulum type vibration isolation device 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 composed of a pendulum in which the object to be isolated (in this case, a television camera for road surveillance) and an added mass are suspended by a hanging material, and a damping mechanism that damps the vibration of the pendulum.By adjusting the length of the pendulum, this vibration isolation device can provide damping and quickly converge residual vibrations while maintaining the natural frequency at a low frequency.

[0014] As shown in Fig. 1, the pendulum type vibration isolation device 10 comprises a hanging material support base part 13, and a plurality of (e.g., three) hanging materials 12 constituting a pendulum are suspended from this hanging material support base part 13. The hanging materials 12 are not particularly limited, and for example, in addition to wires, chains or rods can be used. In either case of the hanging materials 12, the connection part of the upper end with the hanging material support base part 13 is connected by a connecting mechanism such as a pin or universal joint in a state in which pendulum motion is possible.

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

[0016] A damping mechanism 20 is provided between the hanging member support base portion 13 and the vibration-proof object support base portion 14. As shown in FIG. 2, the damping mechanism 20 has a cylindrical container-shaped damping case 21 provided on the vibration-proof object support base portion 14. A viscous fluid tank 23 filled with a gel-like viscous fluid 22, which is 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-shaped recess that has a cross shape when viewed from above. In FIG. 3, (A) is a top view of the damping case 21, (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 serving as a damping member suspended from the hanging member support base portion 13 via a rod 24 is immersed in the viscous fluid bath 23. The width of the viscous fluid bath 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 exerting the effect of damping vibration. In addition, during large displacements, deformation of the viscous fluid 22 between the cross-shaped fin 25 and the side walls of the cross-shaped groove is suppressed, thereby exerting the effect of suppressing large displacements.

[0018] In this embodiment, as shown in Fig. 4, a cross-shaped fin 25 consisting of four fins symmetrically protruding from the axial center toward the periphery at 90° intervals is used as the damping member, but the present invention is not limited to this and a damping member consisting of multiple fins symmetrically protruding from the axial center toward the periphery can be used. For example, various types of damping members can be used, such as a member consisting of three fins symmetrically protruding from the axial center toward the periphery at 120° intervals, or a member consisting of six fins symmetrically protruding from the axial center toward the periphery at 60° intervals. When a member other than the cross-shaped fin 25 is used, the shape of the groove provided in the viscous fluid tank 23 must also be changed.

[0019] The side walls of the cross-shaped grooves may 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 damping of vibrations can be achieved.

[0020] As described above, in this embodiment, the shape of the viscous fluid tank 23 is configured with a cross-shaped groove to match the shape of the cross-shaped fin 25, but 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 for suppressing large amplitude during large displacement. In addition, the width of the cross-shaped groove relative to the shape of the cross-shaped fin 25 can also be adjusted depending on the required damping force and the performance required for suppressing large amplitude during large displacement.

[0021] In this embodiment, the height position of the cross-shaped fin 25 can be adjusted at the attachment portion between the rod 24 and the cross-shaped fin 25, and the immersion depth of the cross-shaped fin 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 fin 25 to some extent, and to easily adjust the resonance frequency.

[0022] As shown in FIG. 2, a cushion 26 is disposed in 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 side of the damping case 21 so as to cover the upper surface of the damping case 21 with a gap therebetween, and the cushion 26 is disposed so as to be interposed between the damping case 21 and the stopper plate 27. The cushion 26 is made of, for example, a low-resilience cushion made of low-resilience urethane foam, has a structure with irregularities on one surface, and is rolled into a cylindrical shape so that the surface with the irregularities faces inward. More specifically, for example, a urethane foam foam with a resilience modulus of 15% or less can be suitably used as the cushion 26.

[0023] In this embodiment, the damping material is a gel-like viscous fluid 22, but a liquid damping material 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 silicon 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, the viscous fluid 22, viscous fluid tank 23, cross-shaped fin 25, cushion 26, stopper plate 27, and other components provided in the damping case 21 generate a damping force against vibration. Of these, the viscous fluid 22, viscous fluid tank 23, and cross-shaped fin 25 act mainly against rotational and horizontal displacements. The cushion 26 and stopper plate 27 act mainly against vertical displacements, suppressing them and absorbing shocks when large displacements occur. The cushion 26 also suppresses large horizontal displacements and absorbs shocks.

[0025] As shown in Fig. 5, the pendulum type vibration isolation device 10 having the above configuration is attached to a support pillar 30 provided on the shoulder or the like of a highway 31, and is adapted to isolate an object to be isolated (here, a television camera for monitoring the road) 11. In this case, the vibration applied to the pendulum type vibration isolation device 10 from the support pillar 30 is 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 requires isolation 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 shows vibration acceleration (dB) and the horizontal axis shows frequency (Hz). The peak on the left side shown in Fig. 6 is the resonance point of the road vibration of the elevated section and 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 shows the vibration before being isolated by the pendulum type vibration isolation device 10. In this embodiment, the pendulum type vibration isolation device 10 is set to have a vibration isolation effect by adjusting its natural frequency to be between the above two peaks.

[0027] Next, an example of comparing transfer functions according to damping performance will be described. In this case, as shown in FIG. 7, the vibration before being damped by the pendulum type vibration isolator 10 is measured by the sensor 40, and the vibration after being damped by the pendulum type vibration isolator 10 is measured by the sensor 41, and the vibration transmissibility is measured by the ratio of (measurement value of sensor 41 / measurement value of sensor 40). The result is shown in FIG. 8. In FIG. 8, the vertical axis is the transfer function (dB) and the horizontal axis is the frequency (Hz). The dotted line shows the actual measurement result, and the solid line shows the predicted value when the damping rate of the pendulum type vibration isolator 10 is adjusted (reduced). As shown in FIG. 8, by adjusting the damping rate of the pendulum type vibration isolator 10, the transfer function can be reduced on average, and in particular, the vibration at the peak of the resonance point of the traffic vibration shown in FIG. 6 can be damped.

[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 implemented 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 in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0029] 10 Pendulum type vibration isolation device 11 Anti-vibration objects 12 Hanging material 13 Hanging material support base 14 Anti-vibration object support substrate 20 Damping mechanism 21 Damping Case 22 Viscous fluid 23 Viscous fluid tank 24 Bar material 25 Cross Fin 26 Cushion 27 Stopper plate 30 pillars 31 Expressway 40,41 Sensors

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 hanging material suspended from the hanging material support base portion; a vibration-proof object supporting substrate portion that is suspended by the suspension material and supports the vibration-proof 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 that is a damping material; a damping member having one end directly or indirectly fixed to the hanging member 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 protruding symmetrically from an axial center toward an 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 cruciform fins; The viscous fluid storage portion is formed of a groove portion arranged in a cross shape on the lower side of the inner side 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 an 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 cushioning material is disposed in an annular shape along the inner side surface of the damping case, and has projections and recesses on the inner side. 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 from vibration 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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