JPH0520544B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a vibration prevention device for a cylindrical structure.

BACKGROUND OF THE INVENTION It is well known that cylindrical structures such as free-standing chimneys generate Karman vortex excitation when subjected to external forces such as relatively low wind speeds. As a countermeasure to this problem, various vibration damping devices have been devised that apply the principle of a so-called dynamic damper.

Problems to be Solved by the Invention Conventional vibration damping devices have been designed to cope with vibrations in the main directions in which the structure in which they are installed is likely to occur. However, cylindrical structures have the problem of having to deal with vibrations in all directions.

The present invention solves the above problems and aims to provide a vibration prevention device for a cylindrical structure that can cope with vibrations in all directions.

Means for Solving the Problems In order to solve the above problems, the present invention provides a mounting beam protruding near the top of a cylindrical structure, and a ring-shaped mounting beam is attached to the mounting beam via a hanging material. A weight is suspended from the ring-shaped weight, and a wire rope is connected to the ring-shaped weight with a coil spring and a damper interposed therebetween to damp the vibration of the ring-shaped weight.

Effect In the above configuration, the natural frequency of the sub-oscillation system, which consists of a weight suspended via a hanging material, a damper and a coil spring connected to this weight via a wire rope, is determined by the natural frequency of the main vibration system. The length of the hanging material or the spring constant of the coil spring is adjusted to match or approach the natural frequency of the cylindrical structure.

If the cylindrical structure vibrates in this state, the vibrations of the secondary vibration system and the main vibration system will cancel each other out, reducing the vibration amplitude of the cylindrical structure.Moreover, the damper and coil spring are connected via the wire rope. Since the dynamic damper is constructed so that it operates in response to the movement of the weight in any direction, it can always be damped in the same way no matter which direction the cylindrical structure vibrates.

Embodiment Hereinafter, an embodiment of the present invention will be described based on the drawings. In FIG. 1, 1 is a cylindrical structure main body, and at least 3
Mounting beams 2 are provided radially. 3
are ring-shaped weights arranged at appropriate intervals around the periphery of the cylindrical structure main body 1.

As shown in detail in FIG. 2, the ring-shaped weight 3 is suspended in a pendulum manner at the tip of the mounting beam 2 via a hanging material 4, and the connecting portions of the upper and lower ends of this hanging material 4 are connected to a universal By incorporating the pins 6a and 6b, the weight 3 can vibrate smoothly in all directions. Reference numeral 5 designates a turnbuckle interposed in the middle of the hanging material 4 for adjusting the length of the hanging material. 7 is a coil spring weighted near the root of the mounting beam 2; 8 is a damper connected to the lower end of the coil spring 7; a wire rope is connected between the lower end of the damper 8 and the ring-shaped weight 3; 9 is the pulley mechanism 1
Connected via 0.

As shown in FIG. 3, the pulley mechanism 10 includes two pulleys 13, 13 rotatably attached to the arm 12 via horizontal pins 11, 11 so that their outer peripheral surfaces face each other, and a cylindrical structure. The wire rope 9 is fixed to the main body 1, supports the other end of the arm 12 via a vertical pin 14, and is made up of an arm mounting bracket 15 that allows the arm 12 to freely rotate in the horizontal direction. 13 and is guided to the ring-shaped weight side.

The damper 8 uses an oil damper or an air damper whose damping coefficient can be finely adjusted, and the size of the weight 3 and damping coefficient are theoretically determined in advance so that the damping effect of the dynamic damper is maximized. I'll keep it.

Next, the effect of the above configuration will be explained. The sub-vibration system formed by the damper 8, coil spring 7, wire rope 9, hanging member 4, and ring-shaped weight 3 is called a dynamic damper, and the natural frequency of this dynamic damper is set to the main vibration system. In order to match or approach the natural frequency of the cylindrical structure main body 1, the length of the hanging member 4 is adjusted by the turnbuckle 5, and the spring constant of the coil spring 7 is reduced so that the pendulum vibration is mainly performed, or the spring constant of the coil spring 7 is The spring constant is selected as the main factor, and the hanging member 4 is made to have the sole role of suspending the ring-shaped weight 3.

If the cylindrical structure main body 1 vibrates in this state, the vibrations of the cylindrical structure main body 1 and the vibrations of the dynamic damper cancel each other out, and the vibration amplitude of the cylindrical structure main body 1 decreases. At this time, the wire rope 9 of the dynamic damper is protected against vibrations in all directions because the pulley mechanism 10, that is, the wire rope 9 is held between two pulleys 13, and the arm 12 is horizontally rotatable. Ring-shaped weight 3
It is possible to follow the movement of

Effects of the Invention As described above, according to the present invention, vibrations of a cylindrical structure body in any direction are mechanically suppressed by a dynamic damper composed of a pendulum-type weight, a damper, a coil spring, and a wire rope. be able to.

[Brief explanation of the drawing]

FIG. 1 is an overall perspective view showing an embodiment of the present invention;
FIG. 2 is a detailed view showing the structure of the dynamic damper, and FIG. 3 is an enlarged perspective view of the pulley mechanism. DESCRIPTION OF SYMBOLS 1... Cylindrical structure body, 2... Mounting beam, 3... Weight, 4... Hanging material, 5... Turnbuckle, 7... Coil spring, 8... Damper, 9... Wire rope, 10... Pulley mechanism, 11... Horizontal Pin, 12... Arm, 13... Pulley, 14... Vertical pin, 15... Arm mounting bracket.

Claims (1)

[Claims] 1. A mounting beam is provided protruding near the top of the cylindrical structure, a ring-shaped weight is suspended from the mounting beam via a hanging material, and a coil spring is installed to damp the vibration of the ring-shaped weight. A vibration prevention device for cylindrical structures characterized by connecting a wire rope with a damper interposed to this ring-shaped weight.