JPH02245531A - Viscous damper - Google Patents

Abstract

PURPOSE:To reduce resistance of a viscous fluid as much as possible so as to stabilize damper property by arranging a pressure absorbing body by which volume is flexibly varied by external pressure in a closed region which is closed by a wall surface in a case and by a fixed body, and which is situated close to the moving edge of a moving body. CONSTITUTION:When a moving plate 4 is moved to the right, in a closed region A on the right corner that is closed by an internal wall surface of a case 1 and by a fixed plate 3, resistance is generated in a viscous fluid 2 being pushed by an edge surface of the moving plate 4, whereby a tube 31 on the right corner is contracted, and the resistance is absorbed thereby. By means of the movement of the moving plate 4, negative pressure is generated in a closed region on the left corner, whereby the tube 31 of left corner is expanded, and the negative pressure is offset. Contraction and expansion of the tube 31 are repeated in reciprocating motion of the moving plate 4, during which reaction to the moving plate 4 is reduced as much as possible. Damper property is thus stabilized.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a viscous damper used for damping vibrations of structures.

(Prior Art) Viscous dampers are broadly classified into flat type and cylindrical type based on their shapes. A flat plate type viscous damper has a structure shown in FIG. 6, for example.

In the figure, reference numeral 1 denotes a box-shaped case in which a viscous fluid 2 is housed. A fixed plate 3 is disposed within the case 1 at a predetermined distance from the bottom of the case 1, and a movable plate 4 is disposed between the fixed plate 3 and the bottom of the case 1. is located. The case 1 is placed on the ground 5, while the movable plate 4 is connected to a hole 4a made in the fixed plate 3.
A strut 8 is inserted through and extends upward, and a structure 7 is supported at the tip of this strut B. In this embodiment, when vibrations such as an earthquake are applied to the ground 4, the movable plate 4 moves horizontally relative to the fixed plate 3 (and case 1) as shown in FIG. A damping force is generated by the resistance force caused by the movable plate 4 shearing the viscous fluid 2, and vibrations transmitted to the structure 7 are alleviated.

On the other hand, a cylindrical viscous damper has a structure shown in FIG. 9, for example. In the figure, reference numeral 11 denotes a cylindrical case, both ends of which are sealed by a bottom plate 12 and an upper lid 13, and a viscous fluid 14 is housed therein. A cylindrical fixed tube 11115 whose lower end is fixed to the bottom plate 12 is disposed inside the case 11, and a movable tube IB is disposed between the fixed tube 15 and the inner wall surface of the case 11. ing.

The upper end of the movable cylinder 18 is covered with a lid 17 having a ventilation hole lea, and a rod 18 extends from the lid 17 to the outside of the case 11, passing through the upper lid 13.

The cylindrical viscous damper 20 is put into practical use by being attached to a 10-pipe 22 for hanging an elevator box 21, as shown in FIG. 10, for example. The rope 22 is hoisted up and lowered by a motor 23, and a spring 24 is interposed at the connection portion to the mebox 21. The viscous damper 20 is connected to the rope 22 in parallel with the spring 24.
and the box 21. When the elevator moves, vibrations from the motor 23 are transmitted to the rope 21,
It is roughly transmitted to the box 21 via the spring 24. Therefore, the box 21 vibrates in the vertical direction and causes a relative movement with the rope 22. Then, the fixed cylinder 13 (and case 11) and the movable cylinder 14 of the viscous damper 20 move relatively, and this relative movement As a result, a resistance force is generated due to shearing of the viscous fluid 14, and vibrations are damped similarly to the flat plate type viscous damper.

(Problems to be Solved by the Invention) By the way, in the above-described viscous damper, the movable body 4.
Since the area near the moving end of the case 1.16 is closed by the inner wall surface of the case 1.11 and the fixed body 3.15, when the movable body 4.1B makes a large relative movement, it is pushed by the end face of the movable body. There is a problem in that an extra resistance force is generated in the viscous fluids 2 and 14, and the damper characteristics are disturbed by a so-called spring action.

To explain this specifically, in the case of a flat plate type viscous damper, when the movable plate 4 moves relatively to the right as shown in FIG. In the closed area A (represented by a black dot) in the right corner,
A reaction force indicated by an arrow a acts on the movable plate 4 from the viscous fluid 2. A similar reaction force also acts when the movable plate 4 moves relative to the left, and as a result, as shown in FIG. 8, a waveform disturbance occurs in the damper characteristics determined as a correlation between displacement and load. Ideally, this waveform should be oval, as shown by the dotted line in Figure 8, but if the waveform is distorted as described above, it will be difficult to achieve the desired damping effect.・ On the other hand, in the case of a cylindrical viscous damper, as shown in Figure 9,
When the movable cylinder 18 relatively moves toward the contraction side (downward in the figure), the movable cylinder 18 moves in the closed region B (represented by a black dot) at the lower corner closed by the inner wall surface of the case 11 (including the bottom plate 12) and the fixed cylinder 15. Viscous fluid for cylinder 1B! A reaction force indicated by the arrow 4 acts, and as a result, as shown in FIG. 11, the waveform of the damper characteristics is disturbed, making it difficult to exert the desired damping effect as described above.

The present invention has been made with the aim of solving the above-mentioned conventional problems. The purpose is to provide a damper.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a fixed body disposed within a case containing a viscous fluid, and a movable body disposed between the fixed body and the inner wall surface of the case. In the viscous damper, which generates a damping force by the resistance force that shears the viscous fluid when the movable body moves relative to the fixed body, the damper is closed by the inner wall surface of the case and the fixed body, and the movable body is closed by the inner wall surface of the case and the fixed body. A feature of the present invention is that a pressure absorber whose volume can be elastically varied by external pressure is disposed in a closed region near the moving end.

In the present invention, the pressure absorber is not limited in type as long as it can change its volume elastically depending on external pressure, and for example, it may be a rubber or plastic tube containing a fluid such as gas or liquid, or a urethane foam. You can choose plastic form such as.

The present invention can also be configured such that instead of providing the pressure absorber in the closed area, a liquid passageway that allows the flow of viscous fluid is provided in a portion of the fixed body corresponding to the closed area. .

(Function) In the viscous damper configured as described above, when the movable body moves relative to the fixed body, the pressure absorbing body contracts or the viscous fluid Since the movable body itself escapes through the liquid passage, the reaction force exerted on the movable body from the viscous fluid is reduced as much as possible, and as a result, the damper characteristics are stabilized.

(Example) Hereinafter, an example of the present invention will be described based on the accompanying drawings. In addition, in the following figure, the above-mentioned 6rI! The same parts as those shown in J or FIG. 9 are given the same reference numerals, and their explanations will be omitted.

FIG. 1 shows a first embodiment of the present invention applied to a flat plate type viscous damper. A tube 31 as a pressure absorber whose volume can be elastically varied by external pressure is disposed in a closed region A near the moving end of the movable plate 4. This tube 31 is formed into an endless ring shape, and air is trapped inside.

With this configuration, as shown in FIG.
When the viscous fluid 2 moves to the right relative to the fixed plate 3, the viscous fluid 2 is pushed by the end face of the movable plate 4 in the closed area A at the right corner closed by the inner wall surface of the case 1 and the fixed plate 3.
A resistance force is generated, but the tube 31 at the right corner contracts in response to this resistance force and absorbs the resistance force. On the other hand, due to the relative movement of the movable plate 4, negative pressure is generated in the closed area at the left corner, and the tube 31 at the left corner expands accordingly.
Offset this negative pressure.

This contraction and expansion of the tube 31 is repeated in conjunction with the reciprocation of the movable plate 4, and during this time, the reaction force applied to the movable plate 4 in the direction of movement is reduced as much as possible.

As a result, as shown in FIG. 3, the waveform representing the damper characteristics becomes oval, and the damper characteristics are stabilized.

FIG. 4 shows a second embodiment of the present invention applied to a cylindrical viscous damper. In the second embodiment, the urethane foam 32 as a pressure absorber is arranged in the closed area B near the moving end of the movable cylinder 1111B. When moving downward, the viscous fluid 14 is pushed by the end face of the movable cylinder 1B in the closed area B.
A resistance force is generated, but the urethane foam 32 contracts in response to this resistance force and absorbs the resistance force. This contraction of the urethane foam 32 is repeated as the movable tube IB moves downward, and during this time, the reaction force applied to the movable plate 4 in the direction of movement is reduced as much as possible, similar to the case of the first embodiment. To (
Figure 3) The damper characteristics are stabilized.

In addition, in the above 1.2 embodiment, the movable body 4.18
When the damper moves excessively and collides with the case l or the bottom plate 12, the tube 31 (Fig. 1) or the urethane foam 32 (Fig. 4) acts as a cushion to prevent damage to the viscous damper. Benefits of prevention can be obtained.

FIG. 5 shows a third embodiment of the present invention applied to a cylindrical viscous damper. Liquid path 33
The point is that it has been established. By providing the liquid passage 33 in this manner, when the movable cylinder 1e moves downward relative to the fixed cylinder 15, the viscous fluid 14 in the closed area B is moved through the liquid passage due to an increase in resistance force. 33 into the fixed cylinder 15, its resistance force is absorbed, and the damper characteristics are stabilized as in the first and second embodiments. In this third embodiment, since the liquid passage 33 is simply provided in the fixed cylinder 15, compared to the case where the above-mentioned pressure absorber is provided,
Simplification of structure can be achieved.

Incidentally, the liquid passage hole may be provided in the fixed plate 3 (FIG. 1) of the flat plate type viscous damper.

(Effects of the Invention) As described above in detail, according to the viscous damper according to the present invention, when the movable body moves relative to the fixed body,
Since a pressure absorber or liquid passage is provided to alleviate the resistance force generated in the viscous fluid within the closed area, the reaction force applied to the movable body from the viscous fluid is reduced as much as possible, making the damper characteristics extremely stable. You can obtain the effect of Also.

Especially when a pressure absorber is placed within a closed area.

The pressure absorber reduces the impact of the movable body against the case, which helps prevent damage to the viscous damper.On the other hand, the structure is simple, especially when liquid passage holes are provided in the fixed body instead of the pressure absorber. This makes manufacturing easier.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention applied to a flat plate type viscous damper, FIG. 2 is a schematic diagram for explaining its damping action, and FIG. 3 is a graph showing its damper characteristics. Fourth
The figure is a sectional view showing a second embodiment of the present invention applied to a cylindrical viscous damper, FIG. 5 is a sectional view showing a third embodiment of the invention similarly applied to a cylindrical viscous damper, and FIG. 6 is a conventional one. 7 is a schematic diagram for explaining its damping effect, and FIG. 8 is a graph showing its damper characteristics.
FIG. 9 is a sectional view of a conventional cylindrical viscous damper, FIG. 10 is a schematic diagram showing its usage, and FIG. 11 is a graph showing its damper characteristics. 1.11... Case 2.14... Viscous fluid 3.14... Fixed body 4.16... Movable body 31... Tube (pressure absorber) 32...
・Urethane foam (pressure absorber) 33...Liquid passages A, B...Closed area Fig. 1 Fig. 4 Fig. 2gA M5 Ink 6 Section Fig. 7 Fig. 8

Claims (2)

[Claims] (1) A fixed body is placed in a case containing a viscous fluid, and a movable body is placed between the fixed body and the inner wall of the case, and when the movable body moves relative to the fixed body, the viscous fluid is sheared. In a viscous damper that generates a damping force by a resistance force, a volume is elastically variable by external pressure in a closed region closed by the inner wall surface of the case and the fixed body and near the moving end of the movable body. A viscous damper characterized by having a pressure absorber arranged therein. (2) The viscous damper described in item 1 is characterized in that, instead of providing a pressure absorber, a liquid passageway is provided in a portion of the fixed body corresponding to the closed region to allow the flow of viscous fluid. viscous damper.