JPH02106585A - Damping device for suspended lineform body - Google Patents

Abstract

PURPOSE:To sufficiently shut off transmission of vibration to a suspended lineform body from a cage and a elevation passage and absorb the vibration by providing a device which is formed such that the one support point of a lineform body can swing within a surface extending at right angles with a tension direction and exerts a centering force. CONSTITUTION:A tail cord 3 being a suspended lineform body is suspended between a swing fulcrum O1' on the cage side below a cage 2 suspended in an elevating tower 1 by means of a main rope 4 and a swing fulcrum O1 on the tower side of an elevating tower 1. The both ends of the tail cord 3 are supported by levitating suspension mechanisms, no tension is exerted on end parts 5 and 6 thereof, and the swing fulcrums and O1 and O1' are formed such that they can horizontally swing. A rail 17 on the tower side is arranged in the direction of an X-axis, and meanwhile a rail 20 on the cage side is situated in the direction of an Y-axis. The two rails 17 and 20 have a slightly recessed central part, and a centering force by which shuttles 13 and 14 are returned to a central part is generated by means of gravity exerted on the tail cord 3.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a vibration damping device for a suspended strip, and is particularly suitable for damping a tail cord that is suspended between the tower side and the cage side of an elevator and hangs down due to its own weight. The present invention relates to a suitable vibration damping device for a suspended strip.

[Conventional technology] Elevators generally have a main rope and a weight compensation rope.

Strings such as governor ropes and tail cords are suspended from the cage, and when the building shakes due to an earthquake, etc., the cage and the elevator tower, which are the fulcrum of the strings, shake horizontally, so these strings also resonate and shake violently. Easy to move. In particular, the tail cord has a low natural frequency among the struts suspended in the elevator tower, and 1
In addition to the natural vibrations of the following modes, vibrations of higher modes often resonate with the natural frequencies of the building, further complicating the problem.

This tail cord is a cord made by bundling and braiding the control lines, power lines, and other wiring necessary between the cage that goes up and down and the elevator tower, and it hangs under its own weight in a narrow and high hoistway. ing. In addition, this tailcoat has weaker tension in the strips than the main rope or weight compensation rope, which has both ends under strong tension, so it has a low natural vibration frequency and is suitable for use in super high-rise buildings when buildings shake due to earthquakes or typhoons. It resonates with the building's natural frequency and tends to swing at low frequencies and large amplitudes.

Therefore, there is a risk that the tail cord, which has swung widely, may collide with the wall of the hoistway, or that the strip may become entangled with other equipment or members, and an accident may easily occur if the elevator is operated with the tail cord entangled.

In order to prevent this accident, elevators are generally equipped with a controlled operation system that suspends operation from the time an earthquake occurs until the shaking of these strips has completely attenuated. It takes a long time for the vibrations of the strip to naturally attenuate, and the elevator stop time must be set to be correspondingly long. In addition, it is common practice to insert anti-vibration rubber between the carrier and the supported object in order to absorb vibrations caused by earthquakes, but if the period of excitation vibration is long, anti-vibration rubber should be inserted in response to this. It is difficult to lower the spring constant. As a countermeasure for this, in railway vehicles, etc., the car body is suspended from the bogie using a mechanism called a floating suspension mechanism so that it can swing horizontally, and a spring with a low spring constant provides a restoring force, and the appropriate horizontal relative movement between the bogie and the car body is applied. A system in which a damper is provided to provide braking force is generally adopted, and a floating suspension mechanism applied to vibration damping of the suspension strip of an elevator is disclosed in Japanese Patent Application Laid-Open No. 55-94045, which is owned by the same inventor as the present application. ``Vibration damping device for vertically suspended flexible wire rods'' and ``Distribution device for hanging strips'' disclosed in Japanese Patent Application Laid-Open No. 57-124145 have already been proposed.

[Problems to be Solved by the Invention] The excitation force to the vehicle body, which is the carrier of the floating suspension mechanism of the above-mentioned railway vehicle, is transmitted unilaterally from the floating suspension mechanism, whereas in the suspension of a strip, the tail cord It is common for both ends to be supported individually at different positions, as shown in the example below. For this reason, a floating suspension mechanism is often provided only at one end. However, in this case, it is unavoidable that vibrations such as those caused by an earthquake will be transmitted to the strip from the support point that does not employ a floating suspension mechanism. As a result of observing wave propagation phenomena in the tail cord of an elevator using a test facility that uses a floating suspension mechanism only at one end of the support point, the following phenomena were observed.

In other words, a transverse wave that shakes one end of the tail cord and is emitted to the tail cord propagates in the longitudinal direction of the tail cord, reaches the other end, and causes the floating wave there! IIJ It is reflected by the suspension mechanism and returns to the original direction. Since some of the wave energy is wasted during this reflection, the reflected wave is attenuated and becomes considerably smaller, but this reflectivity must also be reduced.

In addition, the purpose of the floating suspension mechanism used in railway vehicles, etc. is to absorb the rocking acceleration received from the meandering bogie when the vehicle is running, so the spring constant of the centering device is generally set slightly high. It is designed not to shake too much. On the other hand, the purpose of the floating suspension mechanism for the strip is to prevent the building from shaking with a large amplitude that would cause the strip to hit the shaft wall, even if the building shakes at a low frequency and large amplitude. The object to be measured is the amplitude, not the acceleration of the load. For this reason, it is necessary to make the pivoting force extremely small to make the swinging fulcrum easier to move.

Furthermore, the car body that is supported by a floating suspension system such as a railway vehicle is a single rigid body, and if the braking force applied to the swinging fulcrum in a floating suspension system is extremely strong, the swinging fulcrum will be restrained and will be the same as a fixed fulcrum. As a result, the vibration isolation and absorption effect cannot be exhibited. However, even if the effect of blocking and absorbing vibrations from the road surface is slightly reduced, as shown in the example of the floating suspension mechanism of a railway vehicle, the braking force is It is said that a design with a slightly stronger damping effect is recommended. As a result, the damping rate of free vibration generally exceeds 30%. On the other hand, when the strip is a carrier, the strip is not a rigid body that moves as a whole, but can be bent at any position. 2nd, 3rd
It has the unique property of being able to vibrate in an n-th order higher mode. For this reason, when the braking resistance is increased or the righting force is increased, the swinging fulcrum tends to behave as a constrained fixed fulcrum. In particular, when braking force is applied by Coulomb friction, if the braking force is not extremely reduced, the movement of the swinging fulcrum will intermittently stop, easily inducing incidental self-excited vibration. As a result, high-order vibrations are induced in the strip, causing the strip as a whole to vibrate in a very complex manner, and the fundamental wave of the first mode is no longer effectively absorbed.

The above occurs both when a swinging motion is transmitted from the carrier to the strip body via the floating suspension mechanism, and when a swinging wave is incident on the floating suspension mechanism from the strip body.

Particularly, a unique phenomenon in the case of a strip is that when the freely vibrating strip is attenuated naturally, the swinging fulcrum of the floating suspension mechanism tends to follow the vibration motion of the strip and become unable to swing.

The present invention is intended to solve the above-mentioned new problem, and its purpose is to provide a vibration damping device for a suspended strip that has overall good damping characteristics.

[Means for Solving the Problem] In order to achieve the above object, the present invention configures at least one support point of the strip to be swingable in a plane orthogonal to the tension direction of the strip, and A device is provided that exerts a relatively weak centering force against the swinging of the fulcrum, and to express the magnitude of this centering force, an equivalent equation assumed to be above the dimension R from the swinging fulcrum 01, which is the actual support point, is used to express the magnitude of this centering force. When considering that the suspension strip is supported by a virtual pendulum from the virtual support point o0, the dimension R is set so that the restoring force generated by the gravity of the suspension strip is equal to the above-mentioned restoring force, and this is set as the virtual pendulum. When we call it the radius R, this virtual pendulum radius R becomes 1 of the total length of the suspension strip near the neutral point of the swing. The magnitude of the braking force that acts on the reciprocating motion of this swing fulcrum should be at least twice as much and less than twice as much as the natural damping rate of the first-order mode swing of the suspension strip is at least 10%. It is characterized by being set so that.

[Function] Since the present invention is configured as described above, even if the building shakes due to strata or typhoons, the restoring force and braking force of the floating suspension mechanism are at appropriate values, so vibrations are transmitted from the cage and hoistway to the suspension strip. In addition, if the suspension strip begins to vibrate due to the propagation of seismic motion from the other fixed fulcrum of the suspension strip, the waves incident from the suspension strip will be The floating suspension mechanism, which has sufficient restoring force and braking force, moves to follow this swing, and the damper installed in this part and the braking force generated by the frictional resistance of the floating suspension mechanism themselves. It can consume and absorb the swinging energy of the tail cord. At this time, since the braking resistance is set appropriately, no incidental self-excited vibrations in higher-order modes of the suspended striations are induced.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

Figure 1 is a perspective view of an elevator with a suspension strip vibration damping device, showing the lower car-side swing fulcrum O□' suspended by the main rope 4 in the elevator tower 1, and the A tail cord 3, which is a suspension strip, is suspended between the tower side swing fulcrum 0□.

A pair of brackets 21 are fixed to the wall of the elevator tower 1,
A tower side rail 17 is fixed between the brackets 21. On this tower side rail 17 there is a shuttle 13 which is movable in the horizontal direction by tower side rollers 15, and the tower side steel cord 9 at the end of the tail cord 3 is connected to the shuttle 13 to connect the tower side swing fulcrum O construction. is formed. The end portion 5 of the tail cord is connected to a tower-side junction box 7 provided above a tower-side floating suspension mechanism centered on the shuttle 13 described above.

Further, a substantially horizontal ventral side rail 20 is attached to the lower part of the cage 2 as shown in the figure, and a shuttle 14 is disposed so as to be movable on this side rail 20. A reinforcing steel cord 10, which is peeled off by tearing off the outer covering at the other end of the tail cord 3, is connected to the shuttle 14 to form a cage-side swing fulcrum 01'. The remaining multicore cable end 6 of the tail cord 3 is connected to a junction box 8 attached to I'li 2 to form a floating suspension mechanism.

In this way, both ends of the tail cord 3 are supported by the floating suspension mechanism, so that no tension is applied to the ends 5 and 6, and the swing fulcrum 0□.

0□' is configured to be horizontally swingable. Shuttle 1
3 and 14 are horizontally oscillated, the ends 5 and 6 are elastically deformed, but since the inside is a multicore cable made by twisting many insulated wires together, there is a large energy loss due to internal friction during deformation. The hysteresis of deformation resistance is large. Therefore, when the tail cord 3 swings, the ends 5 and 6 exert a braking force on this swing, thereby consuming the vibration energy. Also, due to the elasticity of the ends 5 and 6 of the tail cord 3, the steel cords 9 and 10 are exposed at point A.

A slight spring action exerts a restoring force against the horizontal swing change of A'.

The tower side rail 17 is arranged in the horizontal X-axis direction, whereas the section side rail 20 is arranged in the Y-axis direction perpendicular thereto. Both rails 17, 20 do not have a horizontal guide surface in the longitudinal direction, but are slightly concave in the center,
Shuttle 13.14 due to gravity acting on tail cord 3
It forms a guide surface on which a centering force is generated that returns the material to its center.

In other words, the guide surface has a downwardly convex arc shape, but its radius of curvature is large, so it is shown as a straight line in the figure.

The position of the center of the circle of curvature near the neutral position of the swing trajectory curve of the shuttle 13, 14 guided by this guide surface is the swing fulcrum 01,0'.

The pendulum whose weight can be ignored is point O8 or ○. Even if you think that the tail cord is suspended from the swing fulcrum o1 or O□' as a weight, the shuttle 1
3.14 guided by rail 17.20 can be realized, and the centering force can be obtained by gravity. now,
If we ignore the bending stiffness of the ends 5 and 6 of the tail cord 3 as zero to simplify the explanation, the centering force will be the same as the rail 17.
It is determined only by the radii R and R' of the 20 arcs, and the radius of the virtual pendulum is R and R' at one point O0, ○. '' is the equivalent virtual support point. Even if a straight rail with a horizontal guide surface is used and only a spring is used to provide the centering force, the weight of the strip is suspended by a virtual pendulum using the same idea. When it is assumed that it coincides with the centering force, this pendulum will be called a virtual pendulum, and the radius of the pendulum will be called the equivalent virtual pendulum radius R.

In this example, strictly speaking, both the centering force due to the trajectory curve of the shuttle 13 and 14 and the centering force due to the spring action of the tail cord ends 5 and 6 act, but in this case as well, the virtual pendulum radius is calculated using the same concept. It is possible to assume that However, the virtual pendulum radius R in this case is slightly smaller than the above value.

The virtual support point O0,00' thus determined and the swing fulcrum 0. ．． 00'' is the virtual pendulum radius R2R'.Since the equivalent virtual pendulum radius R has a dimension of length, take the ratio with the total length Q of the tail cord and calculate this ratio R/ The magnitude of the centering force can be expressed in a dimensionless manner by Q.The centering force acting on the swing fulcrum 01.○,' must be kept as low as necessary, but this The specific numbers will vary depending on the size of the facility.

Since it is necessary to define this requirement in a dimensionless manner, the above-mentioned expression method is used.

In the embodiment shown in the drawings, only the swinging in the X-axis direction is blocked on the tower side, and the swinging in the Y-axis direction is transmitted to the tail cord 3, and only the swinging in the Y-axis direction is blocked on the tower side, and the swinging in the Y-axis direction is blocked. The directional swing is transmitted to the tail cord 3. The vibration in the Y-axis direction transmitted from the tower side to the tail cord 3 is transmitted in the longitudinal direction of the tail cord 3 as a transverse wave and reaches the section side.
There is a floating suspension mechanism that swings in the Y-axis direction, so
The swing fulcrum 01' moves following the swing of the tail cord 3. This swinging fulcrum 0□' has an appropriate amount of braking force due to the hysteresis of the deformation resistance of the tail cord ends 5 and 6, the frictional resistance of the mechanism, etc. Since the natural attenuation rate of the oscillation in the first mode of the strip is set to be greater than the set value described later, the oscillation energy is consumed, and the remaining energy that is not consumed is reflected to the tail cord 3. However, the reflectance of 1 is smaller than 1. The rocking energy in the X-axis direction transmitted from the tail cord 3 to the tail cord 3 is also consumed by the floating suspension mechanism on the opposite tower side, as in the case described above.

According to the experiments conducted by the inventor, the floating suspension mechanism has the effect of blocking and absorbing the transmission of the shaking of the building due to an earthquake to the tail cord 3, and the effect of consuming the wave energy incident on the floating suspension mechanism from the swaying tail cord. In any case, the higher the R/Q ratio, the better the damping effect can be obtained, and under the condition (R/Q) < (1/20), the damping effect is almost completely reduced. I can't enjoy it all the time. Also.

When R/Q exceeds 1, the damping effect does not increase much beyond that, and when R/Q is 2 or less, the increasing tendency of the damping effect is saturated. Therefore,
It is preferable to set it in the range of (1/20)<CR/Q)<2.

Swing fulcrum of floating suspension mechanism 01. Since the appropriate value of the braking force acting on O□' also changes depending on the size of the equipment, it is necessary to express it in a dimensionless manner. In addition, braking force is difficult to express unambiguously because it is a combination of factors with different mechanical properties such as Coulomb friction and viscous resistance. For this reason, the braking force acting during one period of vibration will be comprehensively evaluated and expressed using the natural damping rate of free vibration, as is generally adopted. In a hypothetical method such as the conventional example mentioned above, in which the vibrating support point is suspended in a floating manner to cut off and absorb the transmission of vibration, it is best to limit the braking force to the lowest possible value, so the natural damping rate is also considered in this sense. Infinitely lower is better. However, in this embodiment, if an earthquake occurs while 11w2 is at the top of the hoistway and horizontal vibration of the cage 2 occurs due to the shaking of the building, the swing fulcrum 0□' on the oil side of the tail cord 3 will be Since it is forced to vibrate in the axial direction, it is unavoidable that vibration energy is supplied to the tail cord 3 under resonance conditions.
Therefore, the braking force applied to the tower-side swing fulcrum 01 of the tail cord 3 is large to some extent, and it is necessary to actively absorb the energy in the horizontal floating section. Under conditions where a braking force that satisfies this condition is applied, the natural damping rate for free vibration of the tail cord 3 is 10% or more. However, if this braking force is made too strong, the floating of the horizontal floating suspension mechanism will be restricted and it will become between the fixed fulcrum and the road. In this case, the damping effect of the horizontal floating suspension mechanism on the free vibration of the tail cord 3 decreases, and the damping effect mainly depends on air resistance, resulting in a natural damping rate of 10% or less. As described above, the appropriate braking force has an upper limit value and a lower limit value, and by adjusting the braking force so that the natural damping rate is 10% or more, it can be kept within these ranges. The above-mentioned braking force can be obtained by using the frictional resistance of the floating suspension mechanism itself, internal loss during deformation of the tail cord ends 5 and 6, or by using an independent damper.

In the above embodiment, the floating suspension mechanism that swings in the X-axis direction and the Y-axis direction is distributed to the tower side and the oil side, but it is arranged so that one floating suspension mechanism swings in the X-axis direction and the Y-axis direction. It may be configured. In addition, the floating suspension mechanism may be configured so that the fulcrum of the strip can swing in a direction perpendicular to the tension. For example, point A in the drawing is hung vertically from the machine room of the elevator with a steel cable, and
A damper may be provided at the point. Furthermore, in this embodiment, the tail cord of the elevator was explained, but the main rope,
It can be applied not only to weight compensation ropes and governor ropes, but also to vibration damping devices for power transmission lines and steel cables on suspension bridges, as well as to vibration damping devices for pipes suspended from work vessels floating on the sea and shaking in the waves for resource extraction. be able to.

[Effects of the Invention] As explained above, the present invention appropriately determines the centering force and braking force of the floating suspension mechanism, so it is possible to sufficiently block and absorb the transmission of vibrations to the single strand body. The floating suspension mechanism will work even if it sways.

Swinging energy can be consumed and absorbed by the mechanism's own frictional resistance and braking force from active dampers. In addition, since the braking force is set appropriately in either case, the damping device does not induce incidental self-excited vibrations in higher-order modes of the single-strand body and has good overall damping characteristics. can get.

[Brief explanation of drawings]

FIG. 1 is a perspective view of an elevator using a suspension strip vibration damping device according to an embodiment of the present invention. 3... Tail cord, 5, 6... End, 9, 10... Steel cord, 13.14.
...Sha1~ru. 17...Tower side rail, 20...Part side rail, 0,'...Virtual pendulum support point, 0. 0□' .....Obcillation. Diagram

Claims (1)

[Claims] 1. In a suspension strip vibration damping device in which at least one swing fulcrum of the suspension strip is swingably supported in a plane orthogonal to the tension direction of the suspension strip, A device is provided that exerts a relatively weak centering force, and the magnitude of this centering force is determined by supporting the suspension strip with a virtual pendulum from an equivalent virtual support point assumed above the dimension R from the swing fulcrum. If the above-mentioned dimension R is set so that the centering force generated by the gravity of the suspended strip is equal to the above-mentioned centering force, and this is called the virtual pendulum radius R, the above-mentioned virtual pendulum radius R is 1/2 of the total length of the above suspension strip near the neutral point of the motion.
The magnitude of the braking force acting on the reciprocating motion of the swing fulcrum is set to be 0 times or more and 2 times or less, and the magnitude of the braking force acting on the reciprocating motion of the swing fulcrum is determined by the natural damping rate of the swing of the suspension strip in the first mode. A vibration damping device for a suspended striation, characterized in that the vibration damping device is set to be 10% or more.