RU2370689C2 - Method of dynamic damping and dynamic damper - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: tuning to required damping frequency is performed. Dynamic rigidity or transfer factor dip is experimentally determined at first breadboard specimen. Then on increasing damper slit width, tuning frequency is increased along with increasing damping. Thereafter, tuning frequency is decreased by decreasing damper slit width. Aforesaid reduction is performed by increasing the number of slit pairs. Proposed device comprises interconnected pendulums pivoted to protected object. Each pendulum comprises weight suspended to aforesaid object. One object is located above the points of attachment of its suspension to the object, the others being located below aforesaid points. Tight cylindrical barrel is covered with cap and filled with hydraulic fluid. Movable modular hollow piston is arranged inside aforesaid cylindrical barrel fixed between two cylindrical springs. There is a system of channels inside aforesaid piston. It consists of top and bottom covers and uneven number of round plates. Aforesaid slits are formed by flat round rings arranged between aforesaid covers and plates. Former and latter comprise central bores, while even plates have peripheral orifices arranged nearby inner cylindrical surfaces of round rings.

EFFECT: higher efficiency.

2 cl, 3 dwg

Description

The invention relates to devices for damping vibrations of building objects, especially high-rise structures such as high-rise frame supports, television and radio towers, chimneys and ventilation pipes, masts, etc.

The closest technical solution to the claimed object is a dynamic vibration damper as. USSR No. 920143, E04B 1/98, 1979, containing pendulums connected to each other, pivotally connected to the protected object, each of which has a mass attached to the object by a suspension, and at least one mass is located above the attachment points its suspensions to the object, and the rest below the points of attachment of their suspensions, while at least one mass is connected to the protected object by means of a damping device.

A disadvantage of the known design is that the damper operates reliably and has a simple design at frequencies up to about 0.41 s ^-1 , but at lower frequencies the length of the pendulums and the amplitude of their oscillations are so large that this leads to significant difficulties in the implementation of the damper and its use. In addition, the well-known damper has insufficient damping ability of the oscillations of the pendulums.

The technical result is an increase in the efficiency of dynamic vibration damping by increasing the damping ability of the vibration damper.

This is achieved by the fact that in the method of dynamic damping, which consists in tuning to the required damping frequency, a failure in the dynamic stiffness or in the transmission coefficient at a certain frequency is experimentally obtained on the first prototype, and then the tuning frequency is increased with increasing damping for by increasing the width of the slots of the damper, while increasing the frequency is proportional to the square of the width of the slit, and then lower the tuning frequency by reducing the thickness of the slots of the damper, pr and this lowering of the frequency is proportional to the square of the width of the slit, and lowering the tuning frequency is done by increasing the number of pairs of slots, while the lowering of the frequency is proportional to the square of the number of pairs of slots.

This is achieved by the fact that in a dynamic vibration damper containing pendulums connected to each other by joints, pivotally connected to a protected object, each of which has a mass attached to the object by a suspension, and at least one mass is located above the points of attachment of its suspensions to object, and the rest below the points of attachment of their suspensions, while at least one mass is connected to the protected object by means of a damping device, contains a sealed cylindrical casing-glass, closed with a lid filled with liquid, and inside the cup housing there is a movable hollow piston fixed between two cylindrical springs, which rest with their other ends: the first spring is in the bottom of the cup body, and the second spring is in the cover of the cup, while inside the piston there is a system of channels along which the fluid moves from the upper cavity to the lower cavity when the piston moves up and from the lower cavity to the upper cavity when the piston moves down, while the flow inside the piston occurs along a plane they have slots from the center to the periphery and from the periphery to the center, and the piston is assembled with screws from two caps: the upper and lower and an odd number of round plates, and the cracks are formed by flat circular rings of rectangular cross-section, installed between the covers and plates, while the whole composition forms some the number of pairs of slots, and the upper and lower cover and odd plates contain central holes, and even plates contain the maximum possible number of peripheral holes with a diameter of 2-3 mm, located near internal cyl circular-cylindrical surfaces of the rings.

Figure 1 shows a frontal section of the proposed dynamic vibration damper, figure 2, 3 - diagram of the damping device.

The method of dynamic damping is as follows.

On the first prototype sample, a dip in dynamic stiffness or in the transmission coefficient at a certain frequency is experimentally obtained, and then the tuning frequency is increased with damping due to the increase in the width of the damper slots, while the frequency increase is proportional to the square of the slit width, and then the tuning frequency is reduced by decreasing the thickness damper slots, while lowering the frequency is proportional to the square of the slit width, and lowering the tuning frequency is done by increasing the number of slit pairs , Thus lowering the frequency of performing the square of the number of pairs of slits.

The dynamic vibration damper contains a cylindrical housing-cup 1, a cover 2, tightening bolts 3 with nuts 4, a gasket 5, a plug 6 with a sealing ring, screws for fastening 7 of the housing-cup 1 to the base 17. Inside the housing-cup 1 there is a pre-fabricated hollow piston 8 The piston 8 is sandwiched between the springs 9 and 10 abutting against the cover 2 and the bottom of the housing-cup 1. The piston 8, in turn, consists of the upper and lower covers 11, a package of plates 12 with peripheral holes, a package of plates 13 with central holes. Covers 11 and plates 13 alternate with plates 12. Between all covers and plates, rings of rectangular cross section 14 are installed. The outer diameter of the rings 14 is the same as the inner diameter of the cup body 1. The peripheral holes on the plates 12 are uniformly close to the inner diameter of the rings 14 (see Fig. .2) The diameter of the holes is about 2-3 mm, the distance between the holes is about 2 mm. The piston assembly 8 is tightened with screws 15 with nuts 16.

Dynamic damper operates as follows.

The hydraulic damper operates as follows. Base 17 comes into vibrational motion. This movement is made by the housing-cup 1 with a cover 2. Through the springs 9 and 10, the oscillating motion is transmitted to the piston 8, which makes this movement relative to the housing-cup 1. The fluid filling the entire internal cavity of the hydraulic damper flows from the upper cavity with the spring 9 into the lower cavity with spring 10 and back. The flow is as follows. The piston 8 relative to the housing-cup 1 moves, for example, up. Through a Central hole in the top cover 11, the liquid enters a flat slot between the cover 11 and the plate 12 and spreads along the radii, flowing through the peripheral holes in the plate 12 into the next slot between the plate 12 and the plate 13 with the Central hole and then into the next slot between the plate 13 with a central hole and a plate 12 with peripheral holes, and so on, until it enters the chamber with the spring 10 through the central hole in the lower cover 11. The reduced mass of liquid

where m _CR is the reduced mass, A is the piston area, R is the piston radius, p is the liquid density, h is the slot width, r _o are the radii of the inner holes of the covers 11 and plates 13, n is the number of pairs of slots. From the formula (2) it is seen that a decrease in h and r _o , as well as an increase in n increases the reduced mass. But a decrease in h and r _o leads to an increase in hydraulic resistance, and it is necessary to use more accurate hydrodynamic formulas taking into account the viscosity and inertia of the working fluid. The minimum number of gap pairs is n = 1.

Inside the movable assembled piston is a system of channels through which fluid moves from the upper cavity to the lower cavity when the piston moves up and from the lower cavity to the upper cavity when the piston moves down. The flow inside the piston occurs along flat slots from the center to the periphery and from the periphery to the center. With the relative motion of the liquid, an inertial effect is created, called the effect of the inertial transformer, and with a small mass enclosed in the piston of the liquid, the reduced mass of the liquid moving relative to the housing multiplies. The magnitude of the reduced mass is directly proportional to the number of pairs of slots in which fluid flows and is inversely proportional to the thickness of the slots. The flow occurs in the first slit from the central inlet in the partition and through a large number of small parallel holes at the outer radius in the next partition and vice versa occurs from the periphery to the center. Therefore tuning frequency

where c is the total stiffness of the springs, m _g is the mass of the damper, m _t is the reduced mass of the inertial transformer.

If the failure in dynamic stiffness or in the transmission coefficient at a certain frequency was experimentally obtained at n = 1 in the first prototype sample, then the tuning frequency is increased with increasing damping due to an increase in the width of the slits. Increase the tuning frequency by increasing the width of the slots. The increase in frequency will be proportional to the square of the width of the slit. Reduce the tuning frequency by reducing the thickness of the slots. Reducing the frequency will be proportional to the square of the width of the slit. It is possible to lower the tuning frequency by increasing the number of pairs of slots. The decrease in frequency will be proportional to the square of the number of pairs of slots. Reducing the width of the slots is possible to a certain limit. With a gap width of less than one millimeter, the viscous resistance to fluid flow will destroy the inertial effect.

The proposed device makes it possible by expanding the range of the ratio of the moments of inertia of the mass of the pendulums to significantly reduce the oscillation frequency of the entire damper. At the same time, a significant (1.2-1.4 times) decrease in the dimensions of the damper is achieved, which is very often, especially in high-rise buildings, of great importance.

Claims (2)

1. The method of dynamic damping, which consists in tuning to the required damping frequency, characterized in that the first prototype is experimentally obtained a dip in dynamic stiffness or in the transmission coefficient at a certain frequency, and then increase the tuning frequency with increasing damping for by increasing the width of the slots of the damper, while increasing the frequency is proportional to the square of the width of the slit, and then lower the tuning frequency by reducing the thickness of the slots of the damper, at Ohm, the frequency is reduced in proportion to the square of the width of the slit, and the frequency of tuning is reduced by increasing the number of pairs of slots, while the frequency is reduced in proportion to the square of the number of pairs of slots. 2. A dynamic vibration damper, comprising pendulums connected to each other by joints, pivotally connected to a protected object, each of which has a mass attached to the object by a suspension, at least one mass is located above the points of attachment of its suspensions to the object, and the rest - below the attachment points of their suspensions, while at least one mass is connected to the protected object by means of a damping device, characterized in that it contains a sealed cylindrical casing-glass, closed with a lid and filled with liquid, and inside the housing-cup there is a movable assembled hollow piston fixed between two cylindrical springs, which rest with their other ends: the first spring - to the bottom of the housing-cup, and the second spring - to the cover of the housing-cup, while inside the collection piston there is a system of channels along which the fluid moves from the upper cavity to the lower cavity when the piston moves up and from the lower cavity to the upper cavity when the piston moves down, while the flow inside the piston is flat the pistons from the center to the periphery and from the periphery to the center, and the piston is assembled with screws from two caps: the upper and lower and an odd number of round plates, and the cracks are formed by flat circular rings of rectangular cross-section, installed between the covers and plates, while the whole composition forms a certain number pairs of slots, and the upper and lower lids and odd plates contain central holes, and even plates contain the maximum possible number of peripheral holes with a diameter of 2-3 mm, located near the inner cylinder iCal surfaces circular rings.

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