JP2010265987A - Friction damper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive friction damper applicable to a low-strength structure such as an old existing building. <P>SOLUTION: The friction damper is mounted between two members to be relatively moved for damping vibration between the two members. It includes a motion converting mechanism for converting reciprocative linear moving motion relating to the relative movement into reciprocative rotating motion with a predetermined axial center as a rotating center, a rotary inertia mass rotatably supported on one of the two members around the axial center and adapted to be rotated with the rotating motion, a friction material provided on the rotary inertia mass and adapted to be rotated integrally with the rotary inertia mass, and a sliding material provided on one member for damping vibration with friction force generated between the friction material and itself by sliding motion against the friction material. The motion converting mechanism sets the rotating speed of the friction material around the axial center to be faster than the speed of the linear moving motion. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a friction damper that is interposed between two members that move relative to each other and attenuates vibrations between the two members.

  A friction damper is known as a damping device that is provided between layers of a building and reduces the shaking of the building. As a configuration example of the conventional friction damper, for example, a configuration having a friction material provided on one member that moves relative to each other between layers of a building and a sliding material provided on the other member can be cited. The friction material and the sliding material are in pressure contact with each other with a predetermined pressure, and when sliding, a substantially constant friction force is generated regardless of the amplitude of the interlayer displacement of the building. The frictional force is absorbed as a damping force to reduce the shaking of the building.

JP 2000-352113 A

However, such a conventional friction damper has the following problems.
In the event of a large earthquake, it is necessary to generate a large damping force in order to increase the damping performance, but for that purpose, a large frictional force must be generated, and a large amount of friction members are required, resulting in an increase in cost. .
Further, since the building itself is greatly deformed at the maximum interlayer displacement, a large internal force is generated in the building. In such a case, when a larger external force is applied in the direction opposite to the deformation direction, the internal force is further increased by that amount, and the fracture limit strength is easily reached. Here, the damping force acts as an external force opposite to the deformation direction. Further, the friction damper described above always generates a substantially constant damping force regardless of the magnitude of the interlayer displacement. In other words, according to the above-mentioned friction damper, a building is subjected to a large damping force even under severe internal force at the time of maximum interlayer displacement, and in that case, the building may be damaged depending on the magnitude of the building's failure limit strength. Resulting in. Therefore, it has been difficult to apply the friction damper particularly to a low-strength structure such as an old existing building.

  The present invention has been made in view of the above-described conventional problems, and an object thereof is to provide an inexpensive friction damper that can be applied to a low-strength structure such as an old existing building.

In order to achieve this object, the invention shown in claim 1
A friction damper that is interposed between two members that move relative to each other and attenuates vibration between the two members,
A motion conversion mechanism that converts the reciprocating linear movement operation related to the relative movement into a reciprocating rotation operation about a predetermined axis;
A rotating inertial mass that is supported by one of the two members so as to be rotatable around the axis and is rotated by the rotating operation;
A friction material provided on the rotary inertia mass body and rotating integrally with the rotary inertia mass body;
A sliding material that is provided on the one member and that attenuates the vibration by a frictional force generated between the friction material and the friction material;
The rotational speed of the friction material around the axis is increased by the motion conversion mechanism as compared with the speed of the linear movement operation.
According to the first aspect of the present invention, the rotational speed of the friction material around the axis is increased more than the speed of the linear movement operation. Then, using this speed increase as an insulator magnification, the frictional force in the actual rotational direction between the friction material and the sliding material can be amplified and act as a damping force in the axial direction. As a result, the magnitude of the frictional force in the rotational direction that should actually be generated between the friction material and the sliding material is smaller than the magnitude of the damping force in the axial direction required for vibration damping by a speed increase. Therefore, the friction material and the sliding material can be reduced by the amount that the magnitude of the frictional force is small, and the friction damper can be made inexpensive.

  Moreover, the said structure has a rotation inertia mass body. The negative rigidity effect (described later in detail) based on the inertial force of the rotary inertia mass body becomes larger toward the turning point of the linear movement operation, and is maximized when turning back. Therefore, when turning back the linear movement operation in which a large internal force can be generated in itself due to the deformation of the two members and its neighboring members, the negative rigidity effect of the rotary inertia mass acts in the direction of reducing the damping force, The damping force that is actually input to the two members or the like is smaller than the damping force that is based solely on the frictional force in the rotational direction. Therefore, it is possible to effectively suppress the expansion of the internal force that can occur in the two members or the like due to the input of the damping force, particularly at the time of turning back in a severe internal force state. It can also be applied to structures.

  Furthermore, it can be said that the negative stiffness effect acts in the direction of lowering the stiffness of the structure including the two members. Therefore, the structure can be lengthened, and its damping performance is improved.

The invention shown in claim 2 is the friction damper according to claim 1,
Depending on the speed of the linear movement operation, the rotational speed of the rotating inertial mass changes,
A pressure contact force changing mechanism is provided for changing the pressure contact force of the friction material against the sliding material according to the magnitude of the centrifugal force acting on the rotary inertia mass body.
According to the second aspect of the present invention, the frictional force between the friction material and the sliding material increases or decreases according to the speed of the linear movement operation. Thereby, a speed-dependent friction damper in which the magnitude of the damping force changes according to the speed of vibration is realized. That is, the optimal seismic control action according to the ground motion level can be achieved. More specifically, a small damping force can be generated for a small earthquake with a small vibration speed, and a large damping force can be generated for a large earthquake with a large vibration speed.

The invention shown in claim 3 is the friction damper according to claim 1,
The rotary inertia mass body rotates around the axis, with a predetermined length relating to the linear movement operation as a lead length,
A rotation radius changing mechanism is provided for changing the rotation radius of the rotary inertia mass body according to the speed of the linear movement operation.
According to the third aspect of the present invention, the predetermined length is the lead length. That is, each time the linear movement is performed by the predetermined length, the rotating inertial mass rotates once around the axis. Further, the rotational radius of the rotary inertia mass body, that is, the rotational radius of the friction material increases or decreases according to the speed of the linear movement operation. Then, the sliding length of the friction material per rotation changes by the increase / decrease of the turning radius, that is, the above-described lever magnification changes by the change of the sliding length. And based on this lever magnification, the frictional force in the actual rotational direction between the friction material and the sliding material is amplified and transmitted as the damping force in the axial direction.

  Therefore, according to the above configuration, the magnitude of the damping force increases or decreases according to the speed of the linear movement operation. That is, a speed-dependent friction damper in which the magnitude of the damping force changes according to the vibration speed is realized.

The invention shown in claim 4 is the friction damper according to claim 3,
The turning radius changing mechanism may change the turning radius of the rotating inertial mass body according to the magnitude of a centrifugal force acting on the rotating inertial mass body.
According to the fourth aspect of the present invention, the rotational radius of the rotary inertia mass body, that is, the rotational radius of the friction material is increased or decreased through the centrifugal force in accordance with the speed of the linear movement operation. Thereby, the magnitude of the damping force is passively changed according to the vibration speed through the change in the above-described lever magnification. That is, a passive speed-dependent friction damper is realized.

The invention shown in claim 5 is the friction damper according to claim 4,
The motion conversion mechanism is provided with a rotational motion transmission member that is supported by the one member so as to be rotatable around the axis.
The rotary inertia mass body is rotatably supported by the one member via the rotary motion transmission member,
The rotating radius changing mechanism includes a guide member that allows relative movement in the rotational radius direction while restricting relative movement in the rotational direction of the rotary inertia mass body with respect to the rotational motion transmission member, and the rotary inertia mass body. A first elastic member for applying a centripetal force in the rotational radial direction to
The rotational motion is transmitted to the rotary inertia mass body by rotating the rotational motion transmission member based on the rotational motion converted from the linear movement motion by the motion conversion mechanism,
The rotary inertia mass body is moved to a position in the rotational radial direction where the centripetal force and the centrifugal force are balanced.
According to the fifth aspect of the present invention, the relationship between the damping force and the speed of the linear movement operation (vibration speed) can be easily changed by changing the elastic characteristics of the first elastic member. For example, if the elastic characteristic of the first elastic member is changed to a characteristic in which the elastic force is proportional to the square of the deflection, the damping force and the speed of the linear movement operation can be adjusted so as to have a substantially linear relationship. it can. And the friction damper which has such a linear relationship has the characteristic close | similar to a viscous damper, although it is a friction damper, and becomes a thing which is easy to perform a damping control. Incidentally, friction dampers also have the advantage that they are easier to maintain than viscous dampers.

The invention shown in claim 6 is the friction damper according to claim 5,
At least two of the rotary inertia mass bodies are provided,
The two rotary inertia mass bodies are arranged symmetrically with respect to the axis.
According to the sixth aspect of the present invention, the influence of gravity on the damping force can be almost eliminated. Details are as follows.

In the configuration of the above-described claim 5, when the axial direction is not vertical, gravity acts in the rotational radius direction, which is the movable direction of the rotational inertial mass body, The turning radius of the mass body deviates from the design value.
In this regard, according to the configuration of the sixth aspect, the two rotary inertia mass bodies are arranged symmetrically with respect to the axis. Therefore, even if one rotating inertial mass moves to the inside in the rotational radius direction due to the influence of gravity, the other rotating inertial mass moves to the outside by almost the same amount. When the rotary inertia mass bodies are considered in pairs, the influence of gravity on the rotational radius of the friction material is offset. Therefore, according to the said structure, the influence of gravity can be eliminated substantially.

The invention shown in claim 7 is the friction damper according to claim 5 or 6,
The sliding material and the friction material are arranged to face each other in the axial direction,
A second elastic member for pressing the friction material against the sliding material is interposed between the friction material and the rotary inertia mass body;
The rotary inertia mass body is guided by the guide member so that the position outside the inner position in the radial direction of the rotation is pushed toward the sliding material or vice versa. It is characterized by that.
According to the seventh aspect of the present invention, not only the rotational radius of the rotary inertia mass body, that is, the rotational radius of the friction material, but also the magnitude of the frictional force itself is increased or decreased according to the speed of the linear movement operation. . That is, the damping force is not only increased / decreased based on the lever magnification but also increased / decreased due to the increase / decrease of the frictional force itself. The range of change of force can be adjusted.

The invention shown in claim 8 is the friction damper according to any one of claims 5 to 7,
The motion conversion mechanism has a ball screw mechanism in which a nut portion is screwed to a screw shaft portion via a ball-shaped rolling element,
The nut portion is supported by the one member of the two members while being restricted from moving in the axial direction while allowing rotation around the axial core.
The rotational motion transmitting member is rotatably supported by the one member via the nut portion,
The screw shaft portion is arranged with its axial direction along the direction of the linear movement operation, and one end portion of the screw shaft portion in the axial direction is fixed to the other member of the two members,
The nut portion rotates once for each movement of the nut portion relative to the screw shaft portion by the lead length.
According to the eighth aspect of the present invention, since the motion conversion mechanism has the ball screw mechanism, the linear movement operation can be smoothly converted into the rotation operation.

  According to the present invention, it is possible to provide an inexpensive friction damper that can be applied to a low-strength structure such as an old existing building.

It is a side view of the state which incorporated the friction damper 20 of 1st Embodiment in the brace 10 of the column beam frame 3 of a building. 2 is a longitudinal sectional view of the center of the friction damper 20. FIG. FIG. 3A is a graph showing the relationship between the horizontal displacement of the force point part of the damping force and the internal force generated in the force point part in the column beam structure 3 of the building, and FIG. 3B shows the vibration energy absorption of the conventional friction damper. FIG. 3C is a graph of the history characteristic of vibration energy absorption of the friction damper 20 of the first embodiment. It is a center longitudinal cross-sectional view of the friction damper 20a of 2nd Embodiment. It is a graph of VP relationship of the friction damper 20a of 2nd Embodiment. FIG. 6A is a graph of vibration energy absorption history characteristics of the friction damper 20a, and FIG. 6B is a graph when the negative stiffness effect is small. It is a graph of the VP relationship at the time of using a nonlinear spring for the spring member 47 of the friction damper 20a of 2nd Embodiment. FIG. 8A is a graph of vibration energy absorption history characteristics of the friction damper 20a, and FIG. 8B is a graph when the negative stiffness effect is small. It is explanatory drawing of the structural example which produces a nonlinear spring characteristic by combining several linear coil springs in parallel. It is a center longitudinal cross-sectional view of the modification of the friction damper 20a of 2nd Embodiment. It is a center longitudinal cross-sectional view of the friction damper 20b of 3rd Embodiment.

=== First Embodiment ===
FIG. 1 is a side view of a state in which the friction damper 20 of the first embodiment is incorporated in a brace 10 of a column beam frame 3 of a building. The brace 10 is arranged with the diagonal direction of the column beam frame 3 as a bridging direction. Further, the brace 10 is divided at a position substantially in the center in the bridging direction, which is the longitudinal direction thereof, thereby forming a gap G for interposing the friction damper 20. Specifically, on one side of the gap G, one divided end 10a (corresponding to “one member”, hereinafter also referred to as the first divided end 10a) of the brace 10 is located. On the other side, the other divided end 10b of the brace 10 (corresponding to "the other member", hereinafter also referred to as the second divided end 10b) is located, and these divided ends 10a, 10b are In accordance with the shaking of the building, they can move relative to each other in the spanning direction. Therefore, when the friction damper 20 is interposed in the gap G and is connected to the respective divided ends 10a and 10b, the friction damper 20 has a relative relationship between the divided ends 10a and 10b according to the shaking of the building. Move is entered. Then, based on the input relative movement, the friction damper 20 attenuates the vibration in the bridging direction of the brace 10 and reduces the shaking of the building.

  FIG. 2 is an explanatory diagram of the configuration of the friction damper 20 and is a longitudinal sectional view of the center of the friction damper 20. In this cross-sectional view, a part of the cross-section is omitted from the cross-sectional line in order to prevent complication of the drawing. The same applies to all central longitudinal sectional views used in the following description.

  The friction damper 20 is (1) interposed between the first divided end 10 a and the second divided end 10 b of the brace 10, and spans the relative movement between the divided ends 10 a and 10 b. A ball screw mechanism 30 (corresponding to a “motion conversion mechanism”) that converts a reciprocating linear movement operation in a direction into a reciprocating rotation operation having a direction parallel to the same direction as a rotation center axis C31; And a frictional force generating mechanism 40 that generates a frictional force by sliding and rotating the frictional member 50 with respect to the sliding member 60. This frictional force is used as a vibration damping force.

  The ball screw mechanism 30 includes a screw shaft portion 31 and a nut portion 33 that is screwed onto the screw shaft portion 31 via a ball-shaped rolling element (not shown). The screw shaft portion 31 is disposed with its axial direction C31 parallel to the bridging direction, and one end portion 31b of the axial direction C31 is connected to the second divided end 10b via an appropriate connecting member 32. The relative movement in the axial direction C31 and the relative rotation around the axial center C31 are restricted and connected to the second divided end 10b. On the other hand, the nut portion 33 is connected to the first divided end 10a via a connecting member 35 provided with a bearing 35a, and the nut portion 33 is connected to the first divided end 10a by the action of the bearing 35a. The relative movement in the core direction C31 is restricted, but the relative rotation around the axis C31 is allowed.

  Therefore, when the split ends 10a and 10b move relative to each other in the bridging direction due to the shaking of the building, the nut portion 33 moves relatively linearly along the axial direction C31 of the screw shaft portion 31 according to the relative movement. The nut 33 is screwed and rotated around the axis C31 by this linear movement operation. That is, the linear movement operation related to the relative movement between the divided ends 10a and 10b is converted into a rotation operation around the axis C31. This rotational motion is transmitted to the frictional force generation mechanism 40 and is used for damping vibration through generation of the frictional force in the mechanism 40.

  The frictional force generating mechanism 40 includes: (1) a disk-like flange portion 41 that extends from the outer periphery of the nut portion 33 outward in the rotational radius direction and rotates around the shaft core C31 integrally with the nut portion 33. (Corresponding to “rotational motion transmitting member”), (2) a substantially block-shaped rotational inertial mass 43 integrally provided at a predetermined portion in the rotational direction of the flange portion 41, and (3) the rotational inertial mass 43 A friction material 50 provided via a compressed spring member 45 (corresponding to a “second elastic member”) and rotating integrally with the rotary inertia mass body 43; and (4) while facing the flange portion 41. The sliding member 60 is fixed so as not to move to a portion of the connecting member 35 closer to the first divided end 10a than the bearing 35a.

  Then, the sliding member 60 has a donut-shaped disk shape with the shaft core C31 as a center, and thereby, on the entire circumference of the circular orbit of the friction material 50 rotating around the shaft core C31. It is comprised so that it may contact | abut to the friction material 50 reliably. Therefore, the friction material 50 pressed against the sliding material 60 using the elastic force of the spring member 45 as a pressure contact force generates a substantially constant friction force over the entire circumference of the orbit, and the friction force causes the building to shake. Effectively attenuates.

  Here, the rotational speed of the friction material 50 is higher than the speed V of the linear movement operation in the axial direction C31 of the nut portion 33 by adjusting the lead length L of the ball screw mechanism 30 and the rotation radius r of the friction material 50. It is set to be fast. Specifically, when the nut portion 33 moves linearly relative to the screw shaft portion 31 by the lead length L, the nut portion 33 rotates once around the axis C31, and thus the friction material 50 also rotates once. In the first embodiment, the rotation radius r of the friction material 50 is set so that the circumferential length (= 2π × r) for one rotation is longer than the lead length L.

  And if it is set in this way, the frictional force in the actual rotational direction due to the sliding of the friction material 50 and the sliding material 60 is the ratio of the circumferential length to the lead length L (= 2π × r / L). It can be amplified by the amount and act as a damping force in the axial direction. Conversely, the frictional force in the actual rotational direction can be made smaller than the magnitude of the damping force in the axial direction necessary for vibration damping by the amplification amount by this ratio. 60 weight reduction can be achieved. For example, when this ratio is set to 50 times, the frictional force in the rotational direction that is 1/50 of the required damping force in the axial direction is generated. A damping force in the axial direction of the size can be ensured. Hereinafter, the ratio (= 2π × r / L) related to this amplification is referred to as an insulator magnification.

  Further, the frictional force generating mechanism 40 described above has a rotary inertia mass body 43. Therefore, the negative stiffness effect based on the inertial force of the rotational operation of the rotary inertia mass body 43 can reduce the load applied to the building at the time of vibration damping. It can also be applied to strength structures. Details are as follows.

  FIG. 3A shows a horizontal displacement of a portion to which a damping force is applied by a friction damper (hereinafter referred to as a force point portion (see FIG. 1)) and an internal force generated in the force point portion in the column beam structure 3 of the building. It is a graph which shows a relationship. FIG. 3B is a graph of vibration energy absorption history characteristics of a conventional friction damper, and FIG. 3C is a graph of vibration energy absorption history characteristics of the friction damper 20 of the first embodiment. In both graphs of FIGS. 3B and 3C, the vertical axis represents the damping force P, and the horizontal axis represents the amount of vibration displacement in the bridging direction, that is, the amount of linear movement in the same direction.

  As shown by a solid line in FIG. 3A, since the building itself is greatly deformed at the maximum displacement of vibration, a large internal force is generated in each part of the building. In such a case, if a larger external force is applied in the direction opposite to the deformation direction, the internal force further expands by the amount of the external force at the force point portion to which the external force is applied. That is, the internal force of the force point portion is obtained by adding the internal force generated by the external force to the internal force generated by the deformation of the force point portion itself shown by the solid line in FIG. 3A.

  Here, the damping force P of the friction damper also acts as an external force opposite to the deformation direction. In the case of the conventional friction damper, as shown in FIG. 3B, the magnitude of the damping force P, which is the friction force, is substantially constant regardless of the displacement amount related to the vibration. Therefore, the actual internal force of the power point portion obtained by adding the internal force generated by the damping force P in FIG. 3B to the internal force indicated by the solid line in FIG. 3A is as shown by the dotted line in FIG. 3A. That is, according to the conventional friction damper, a large internal force due to a large damping force P is additionally generated at the force point portion of the column beam frame 3 even under severe internal force at the maximum displacement of vibration. In this case, the internal force is increased, and the breaking limit strength of the force point portion is easily reached. Therefore, it is difficult to apply a conventional friction damper to a low-strength structure such as an old existing building.

  On the other hand, according to the friction damper 20 of the first embodiment, as shown in FIG. 3C, the damping force P becomes smaller toward the maximum displacement of vibration based on the negative stiffness effect. Here, the negative rigidity effect means that the force for urging in the direction opposite to the displacement direction increases as the displacement is performed. In the case of the friction damper 20 of the first embodiment, the inertial force due to the rotation of the rotary inertia mass body 43 is the force that is the source of the negative stiffness effect. Then, the damping force P actually applied to the power point portion is smaller than the damping force based on the frictional force between the friction material 50 and the sliding material 60 by the amount of this inertial force.

  Therefore, the actual internal force obtained by adding the internal force generated by the damping force P in FIG. 3C to the internal force indicated by the solid line in FIG. 3A is as shown by a one-dot chain line in FIG. 3A. In other words, according to the friction damper 20 of the first embodiment, the damping force P decreases as the maximum displacement of the vibration is approached, so that the internal force at the power point portion accompanying the input of the damping force P is increased in a particularly severe internal force state. It can be effectively suppressed at the maximum displacement. As a result, the friction damper 20 can be applied to a low-strength structure such as an old existing building.

Incidentally, the negative stiffness effect increases in proportion to the vibration displacement (that is, the damping force P in FIG. 3C decreases in proportion to the vibration displacement). This is because the acceleration which is the second derivative of the displacement is also a sine wave.
Further, in order to further expand this negative rigidity effect, an annular rib portion 41b may be provided integrally along the outer peripheral edge of the flange portion 41 as shown in FIG. 2 so as to function as a rotary inertia mass body.

=== Second Embodiment ===
FIG. 4 is a central longitudinal sectional view of the friction damper 20a of the second embodiment.
In the above-described first embodiment, the rotational inertia mass body 43 and the friction material 50 are restricted from moving in both the rotational direction and the rotational radial direction with respect to the flange portion 41 of the nut portion 33. In this second embodiment, however, The rotation radius changing mechanism is mainly different from the rotation radius changing mechanism in that only the movement in the rotation direction is restricted and the movement in the rotation radius direction is allowed. Based on this difference, the friction damper 20a of the second embodiment is configured as a speed-dependent friction damper in which the magnitude of the damping force P changes according to the vibration speed V. The other points are generally the same as those in the first embodiment, and in the following, the same reference numerals are given to the same components, and detailed descriptions thereof are omitted.

  As shown in FIG. 4, the turning radius changing mechanism includes a rail 42 (corresponding to a “guide member”) provided on the flange portion 41 along the turning radius direction. Then, by the engagement of the rail 42 with the guide surface 42a, the rotary inertia mass body 43 is guided to be movable in the rotational radius direction while maintaining a constant distance from the sliding material 60. Further, a wall 41a is formed in an annular shape along the outer peripheral edge of the flange 41, and a spring member 47 ("" is formed between the annular wall 41a and the rotary inertia mass body 43. Corresponding to a “first elastic member”. Then, due to the elastic force of the compression deformation of the spring member 47, a centripetal force directed inward in the rotational radial direction is applied to the rotary inertia mass body 43. Therefore, the rotational inertial mass body 43 moves to a position in the rotational radial direction where the centripetal force and the centrifugal force acting on the rotational inertial mass body 43 are balanced.

  Here, the centrifugal force acting on the rotary inertia mass body 43 increases and decreases according to the speed of the linear movement operation of the ball screw mechanism 30, that is, the magnitude of the vibration speed V. Therefore, the rotational radius r1 of the rotary inertia mass body 43 determined by the balance between the centrifugal force and the elastic force of the spring member 47 also changes in accordance with the magnitude of the vibration speed V.

  In addition, the above-described amplification factor for amplification increases / decreases depending on the magnitude of the rotation radius r1, that is, the damping force P obtained by amplifying the frictional force by the leverage factor also changes according to the rotation radius r1. Therefore, according to the configuration of the second embodiment, the magnitude of the damping force P changes in accordance with the magnitude of the vibration speed V, thus realizing a speed-dependent friction damper.

  The damping characteristic of such a speed-dependent friction damper, that is, the relationship between the damping force P and the vibration speed V can be grasped in detail by conducting the following mechanical examination.

First, it is assumed that the spring member 47 is a linear spring (that is, when the elastic force of the spring member 47 is a linear function of deflection), the spring constant is k1, and the deflection of the spring member 47 is zero and not yet. The radius of rotation of the friction material 50 during vibration is r0, and the radius of rotation of the friction material 50 during vibration is r1. Then, the centripetal force Fc applied to the rotary inertia mass body 43 is given by the restoring force (elastic force) of the spring member 47, that is, can be expressed by the following formula 1.
Fc = k1 × (r1−r0) (1)
Also, the vibration speed (that is, the speed of the linear movement operation of the nut portion 33 with respect to the screw shaft portion 31) is V, the lead length of the ball screw mechanism 30 is L, and the mass of the rotary inertia mass body 43 is m1. Then (the masses of the friction material 50 and the spring member 45 are ignored), the centrifugal force Fe applied to the rotary inertia mass body 43 and the friction material 50 can be expressed by the following equation 2.
Fe = m1 × {(2π × r1 / L) × V} ² / r1 (2)
Then, the following formula 3 is obtained by the balance between the centripetal force Fc and the centrifugal force Fe.
k1 × (r1−r0) = m1 × {(2π × r1 / L) × V} ² / r1 (3)
Solving this for r1, the following equation 4 is obtained.
r1 = (k1 × r0) / {k1−m1 × (2π / L) ² × V ² } (4)
Note that when the denominator of the above equation 4 is zero, that is, when V ≧ √ (k1 / m1) × L / (2π), r1 diverges and the turning radius r1 becomes infinite. The rotary inertia mass body 43 and the friction material 50 are in a state of being supported by the annular wall portion 41a so that the rotation radius r1 does not increase any more.

On the other hand, the damping force P of the friction damper 20a is expressed by the following equation based on the above-mentioned concept of the lever magnification, where μ is the friction coefficient of the friction material 50 and the sliding material 60, and N is the pressing force of the friction material 50 to the sliding material 60. It can be expressed as 5.
P = (2π × r1 / L) × (N × μ) (5)
However, the above formula 5 is a case where the rotary inertia mass body 43 and the friction material 50 are one set. In the case of a plurality of sets, the damping force is a multiple of the above formula 5. For example, in the example of FIG. 4, since there are two sets, the number is doubled.
Substituting the above equation 4 into r1 of the above equation 5, the following equation 6 is obtained.
P = (k1 × r0) / {k1−m1 (2π / L) ² × V ² } × (2π / L) × (N × μ) (6)
Then, when the damping force P of the friction damper 20a is graphed based on the expression 6, the VP relationship of FIG. 5 is obtained. That is, as can be seen from the above equation 6 and FIG. 5, it can be seen that a speed-dependent friction damper in which the damping force P changes according to the vibration speed V is realized.
Incidentally, the values described in FIG. 5 are used for the values of r0, k1, L, N, and μ necessary for this graphing, and m1 is shown in FIG. So we are shaking at three levels.

  FIG. 6A shows the vibration energy absorption history characteristics of the friction damper 20a. The vertical axis represents the damping force P, and the horizontal axis represents the amount of vibration displacement in the bridging direction, that is, the amount of linear movement in the same direction. FIG. 6A is a graph when the vibration to be damped is a sinusoidal vibration with time as a variable. The solid line in FIG. 6A is when the vibration speed V is high, and the dotted line is when the vibration speed V is low.

As is clear from FIG. 6A, a large damping force P is generated when the vibration velocity V is large, and a small damping force P is generated when the velocity V is small. Therefore, according to the friction damper 20a of the second embodiment, a small damping force P is generated for a small earthquake with a small vibration speed V, and a large damping force is generated for a large earthquake with a large vibration speed V. P can be generated.
In FIG. 6A, the graph is slanted as a whole because of the negative stiffness effect. In other words, when the negative stiffness effect is small, it becomes substantially horizontal as shown in FIG. 6B.

By the way, it is desirable that the VP relationship in FIG. 5 is linear, and if that is the case, the friction damper is generally used based on the linear relationship for the same reason that the damping control is easy to control. The damper 20a is also easy to design for damping. With respect to this point, in the configuration of the second embodiment, as a method for making the VP relationship substantially linear, the spring member 47 has a characteristic in which the elastic force is proportional to the square of the bending with respect to the spring member 47 described above. Is used.
The fact that a substantially linear VP relationship can be created by the spring member having such spring characteristics can be confirmed as follows by the mechanical examination as described above.

First, as described above, the spring member 47 in FIG. 4 is a non-linear spring whose elastic force is proportional to the square of the deflection. Further, the bending radius of the spring member 47 is zero, and the rotation radius of the friction material 50 when not vibrating is r0, and the rotation radius of the friction material 50 when vibrating is r1. In that case, the centripetal force Fc applied to the rotary inertia mass body 43 is given by the restoring force (elastic force) of the spring member 47, that is, can be expressed by the following Expression 7.
Fc = k1 × (r1−r0) ² (7)
Further, the centrifugal force Fe applied to the rotary inertia mass body 43 can be expressed by the following equation 8 as in the above equation 2.
Fe = m1 × {(2π × r1 / L) × V} ² / r1 (8)
Then, the following formula 9 is obtained by balancing the forces of the centripetal force Fc and the centrifugal force Fe.
k1 × (r1−r0) ² = m1 × {(2π × r1 / L) × V} ² / r1 (9)
Solving this with r1, the following equation 10 is obtained.
r1 = [k1 × L ² × r0 + 2π × {m1 × π × V ² + √ {m1 × V ² × (k1 × L ² × r0 + m1 × π ² × V ² )}}] / (k1 × L ² )… (Ten)

On the other hand, the damping force P of the friction damper 20a is based on the above-described concept of the lever magnification, where μ is the friction coefficient of the friction material 50 and the sliding material 60, and N is the pressing force of the friction material 50 to the sliding material 60. It can be expressed by Equation 11.
P = (2π × r1 / L) × (N × μ) (11)
However, as described above, the above formula 11 is a case where the rotary inertia mass body 43 and the friction material 50 are one set. In the case of a plurality of sets, the damping force is a multiple of the above formula 11. For example, in the example of FIG. 4, since there are two sets, the number is doubled.

Substituting Equation 10 into r1 in Equation 11 above yields Equation 12 below.
P = (2π × N × μ) × [k1 × L ² × r0 + 2π × {m1 × π × V ² + √ {m1 × V ² × (k1 × L ² × r0 + m1 × π ² × V ² )}} / (K1 × L ³ )… (12)
Then, when the damping force P of the friction damper 20a is graphed based on the equation 12, the VP relationship of FIG. 7 is obtained. That is, the VP relationship is almost linear.

FIG. 8A shows vibration energy absorption history characteristics exhibited by the friction damper 20a having a substantially linear VP relationship. The solid line in FIG. 8A is when the vibration speed is high, and the dotted line is when the vibration speed is low. As can be seen from the comparison with FIG. 6A, the hysteresis characteristic loop of FIG. 8A is rounder than that of FIG. 6A, and thus the VP relationship is similar to that of a speed proportional damping device such as a viscous damper. You can see that it has.
In FIG. 8A, the graph is slanted as a whole because of the negative stiffness effect as described above. In other words, when the negative stiffness effect is small, it becomes substantially horizontal as shown in FIG. 8B.

  The nonlinear spring in which the elastic force is proportional to the square of the deflection can be realized by a special spring such as a disc spring or a leaf spring, but can also be realized by a coil spring. For example, a coil spring in which the winding diameter changes along the axial direction of the coil spring, a coil spring in which the wire diameter changes along the axial direction of the coil spring, or a shaft Examples thereof include a coil spring in which the winding pitch in the direction changes in the axial direction.

  In addition, as a method for creating the above-described nonlinear spring characteristics with a coil spring, a method in which linear coil springs having different stiffnesses (spring constants) are arranged in parallel may be used. FIG. 9 is an enlarged view of the frictional force generating mechanism 40a for explaining this method. In this example, the rigidity varies depending on the winding diameter, that is, the coil spring 47a having a large winding diameter indicated by a one-dot chain line in the figure is used as a low-rigidity spring, and the winding diameter indicated by a dotted line in the figure. The coil spring 47b having a medium diameter is used as a medium rigidity spring, and the coil spring 47c having a small winding diameter indicated by a solid line in the drawing is used as a high rigidity spring.

  In the initial bending deformation, a resilient force is applied by the low-rigidity coil spring 47a having a large winding diameter, and in the intermediate bending deformation, the winding is performed in addition to the resilient force of the coil spring 47a. A resilient force is applied from the medium-rigid coil spring 47b having a medium diameter, and in the later bending deformation, in addition to the resilient force of the coil springs 47a and 47b, a highly rigid coil having a smaller winding diameter. A resilient force is also applied from the spring 47c, whereby the above-described nonlinear spring characteristic is realized.

  By the way, in the configuration of the second embodiment (see FIG. 4), when the axial direction C31 of the ball screw mechanism 30 is not vertical, gravity acts in the rotational radius direction that is the movable direction of the rotary inertia mass body 43. As a result, the rotation radius r1 of the rotary inertia mass body 43 is deviated from the design value by the action of the gravity. As a result, the turning radius r1 of the friction material 50 cannot be set as designed, and the desired damping force P may not be obtained.

  Here, in order to eliminate the influence of such gravity, as shown in FIG. 4, at least two rotary inertia mass bodies 43 are provided, and these two rotary inertia mass bodies 43, 43 are mutually connected. It is desirable to arrange them symmetrically facing the axis C31. In this way, even if one rotating inertial mass 43 moves to the inside in the rotational radius direction due to the influence of gravity, the other rotating inertial mass 43 is on the other side approximately the same amount outside. If these rotary inertia mass bodies 43, 43 are considered as a pair, the influence of gravity on the rotation radius r1 of the friction material 50 is offset. Therefore, according to this structure, the influence of gravity can be almost eliminated.

  In the second embodiment described above, the rotary inertia mass body 43 is guided by the guide surface 42a of the rail 42 so as to be movable in the rotational radius direction while maintaining a constant distance from the sliding material 60. However, the present invention is not limited to this. For example, as shown in FIG. 10, by changing the shape of the guide surface 42 c of the rail 42 b, the distance between the sliding material 60 and the rotation of the rotary inertia mass body 43 is changed. You may make it change according to the position of a radial direction.

  More specifically, the guide surface 42c of the rail 42b in the example of FIG. 10 is formed as an inclined surface that protrudes toward the sliding material 60 from the inner side to the outer side in the rotational radius direction. As a result, the rotary inertia mass body 43 is pushed toward the sliding material 60 as it moves from the inner side to the outer side in the radial direction of rotation, so that the spring member 45 between the rotary inertia mass body 43 and the friction material 50 is elastic. Through the change of the force, the pressing force of the friction material 50 to the sliding material 60 becomes higher at the outer position than the inner position in the rotational radius direction, and as a result, the outer position than the inner position friction force. The friction force is higher. In other words, in addition to the above-described change in the lever magnification, the frictional force itself can be changed, whereby the change width of the damping force P with respect to the change in the vibration speed V can be increased.

Incidentally, in some cases, the inclination direction of the guide surface 42c of the rail 42b may be reversed with respect to the configuration of FIG. That is, the guide surface 42c of the rail 42b may be formed as an inclined surface that protrudes toward the sliding material 60 from the outer side toward the inner side in the rotational radius direction. In this case, the rotary inertia mass body 43 is pushed out toward the sliding member 60 as it moves from the outer side to the inner side in the radial direction of rotation, so that the spring member 45 between the rotary inertia mass body 43 and the friction member 50 is pushed. Through the change in the elastic force, the pressure contact force of the friction material 50 to the sliding material 60 is higher at the inner position than at the outer position in the rotational radius direction, and as a result, the inner force is higher than the friction force at the outer position. The frictional force at the position of is higher.
Furthermore, in the first and second embodiments described above, the friction coefficient μ between the sliding material 60 and the friction material 50 is constant over the entire region in the rotational radius direction, but depending on the position in the rotational radius direction. The friction coefficient μ may be varied to change the friction force.

=== Third Embodiment ===
FIG. 11 is a central longitudinal sectional view of the friction damper 20b of the third embodiment.
In the second embodiment described above, the change in the rotation radius r1 of the rotary inertia mass body 43 and the friction material 50 due to centrifugal force is used to realize the speed-dependent friction damper. In the third embodiment, The rotation radius r1 is generally fixed. Instead, the pressure force of the friction material 50 against the sliding material 60 is changed by the centrifugal force of the rotary inertia mass body 73, and the damping force P is changed through the change of the frictional force between the friction material 50 and the sliding material 60. Is changing.

  The change of the pressing force according to the centrifugal force is performed by the pressing force changing mechanism 70. The press contact force changing mechanism 70 has an arm member 72 connected to the outer peripheral portion of the nut portion 33 via a hinge 71 as a main body. By this hinge 71, the arm member 72 is allowed to swing and rotate in a direction in which the arm member 72 approaches and separates from the sliding material 60, but other operations are restricted.

  In addition, a rotary inertia mass body 73 is integrally fixed to the arm member 72, and a centrifugal force generated in the rotary inertia mass body 73 is used as a driving force for the swinging rotation operation of the arm member 72 described above. That is, when the rotation speed of the nut portion 33 increases, the moment in the direction of pushing the arm member 72 toward the sliding material 60 increases through an increase in the centrifugal force of the rotary inertia mass 73, and conversely, when the rotation speed decreases. As the centrifugal force decreases, the moment decreases.

  For the purpose of stabilizing the operation of the arm member 72 when rotation is stopped, the arm member 72 and the flange portion 41 may be connected by a spring member 74 as shown in FIG. A damping member 75 such as an oil damper may be interposed between the arm member 72 and the flange portion 41 in order to suppress vibration of itself.

  On the other hand, the flange portion 41 is located closer to the sliding member 60 in the axial direction C31 than the arm member 72. Further, the flange portion 41 has an axial direction C31 corresponding to the position of the arm member 72. A through-hole 41h is formed. A connecting member 77 (which includes a spring member 78 in the illustrated example) for connecting the arm member 72 to the friction material 50 is inserted into the through hole 41h, and the arm member is interposed through the connecting member 77. The moment 72 is transmitted to the friction material 50, and the friction material 50 is pressed against the sliding material 60.

  Here, as described above, the moment is generated by the centrifugal force acting on the rotary inertia mass body 43, and the centrifugal force changes according to the rotation speed of the nut portion 33, and the rotation speed of the nut portion 33 is It increases or decreases according to the speed of the linear movement operation related to the ball screw mechanism 30, that is, the vibration speed V. Therefore, the pressing force when pressing the friction material 50 against the sliding material 60 based on the moment also changes according to the magnitude of the vibration speed V. Thus, according to the configuration of the second embodiment, the vibration Thus, a speed-dependent friction damper is realized in which the magnitude of the damping force P, which is a friction force, increases or decreases according to the speed V.

  Note that the details of the VP relationship of the speed-dependent friction damper can be confirmed through the following mechanical examination, as in the case of the second embodiment described above.

First, assuming that the rotational radius of the rotary inertia mass body 73 and the friction material 50 is r1, and the distance in the rotational radius direction between the rotary inertia mass body 73 and the hinge 71 is r2, the centrifugal force F1 applied to the rotary inertia mass body 73. Can be expressed by the following equation (13).
F1 = m1 × {(2π × r1 / L) × V} ² / r1
= M1 x r1 x {(2π / L) x V} ² (13)

If the distance in the axial direction C31 between the rotary inertia mass 73 and the hinge 71 is r3 and the damping force by the damping member 75 is 0, the centrifugal force F1 is pressed against the axial direction C31 via the arm member 72. Since the force N is converted to the force N, a balance equation of moments around the hinge 71 as shown in the following equation 14 is established. Then, by solving this with respect to N and obtaining Expression 15, and substituting the above Expression 13 into F1 of Expression 15, the pressure contact force N can be expressed by the following Expression 16.
F1 × r3 = N × r2 (14)
N = F1 × (r3 / r2) (15)
= M1 x r1 x (r3 / r2) x {(2π / L) x V} ² (16)
Here, the friction material 50 is pressed against the sliding material 60 by the pressure N, and the friction force F2 is generated. Therefore, when the friction coefficient at this time is μ, the frictional force F2 can be expressed by the following expression 16, and the above expression 17 is obtained by substituting the above expression 16 into N of the expression 16.
F2 = μ × N (16)
= Μ × m1 × r1 × (r3 / r2) × {(2π / L) × V} ² (17)

On the other hand, the damping force P of the friction damper 20b can be expressed by the following equation 18 from the rotation radius r1 and the friction force F2. However, as described above, the following equation 18 is a case where the rotary inertia mass body 73 and the friction material 50 are one set, and in the case of a plurality of sets, the damping force is a multiple of the following equation 18. For example, in the example of FIG. 11, since there are two sets, the number is doubled.
P = (2π × r1 / L) × F2 (18)
Then, substituting equation 16 into F2 in equation 18 yields equation 19 below.
P = μ × m1 × r1 ² × (r3 / r2) × (2π / L) ³ × V ² (19)
Therefore, as apparent from the above equation 19, the VP relationship is such that the damping force P changes depending on the vibration speed V, and thus it can be seen that a speed-dependent friction damper is realized. .

=== Other Embodiments ===
As mentioned above, although embodiment of this invention was described, this invention is not limited to this embodiment, The deformation | transformation as shown below is possible in the range which does not deviate from the summary.

  In the above-described embodiment, the ball screw mechanism 30 is used as an example of a motion conversion mechanism that can convert a linear movement operation and a rotation operation to each other. A mechanism other than the mechanism may be applied. For example, a rack and pinion mechanism may be used.

  In the second embodiment described above, the spring member 47 is interposed between the annular wall portion 41a and the rotary inertia mass body 43 in order to impart a centripetal force to the rotary inertia mass body 43, and the elastic force of the compression deformation is provided. Although it has been given to the rotary inertia mass body 43, it is not limited to this as long as an centripetal force can be given. For example, a spring member may be interposed between the outer peripheral surface of the nut portion 33 and the rotary inertia mass body 43, and the elastic force of the tensile deformation may be used as the centripetal force of the rotary inertia mass body 43.

  In the above-described embodiment, the friction dampers 20, 20a, and 20b are applied to the braces 10 of the column beam frame 3. However, the application target is not limited to this, and the friction dampers 20, 20a, and 20b may be applied between two relatively moving members. Is possible.

  The friction damper 20a of the second embodiment described above is a passive friction damper 20a that passively changes the rotation radius r1 of the rotary inertia mass body 43 and the friction material 50 by the centrifugal force acting on the rotary inertia mass body 43. However, the present invention is not limited to this, and an active friction damper may be used. For example, an actuator such as a hydraulic cylinder or a motor that moves the friction material 50 in the rotation radius direction is provided, and the friction material 50 is moved in the rotation radius direction according to the vibration speed V by controlling the actuator to rotate the friction material 50. The radius r1 may be changed. Furthermore, the friction damper may be configured to be semi-active by adding the above-described actuator to the above-described passive friction damper 20a.

  In the above-described embodiment, the material of the friction material 50 and the sliding material 60 has not been described. However, any material can be used as long as an appropriate frictional force is generated between the two 50 and 60 during sliding. is there. For example, when a stainless steel plate is used for the sliding material 60, the friction material 50 is provided with tetrafluoroethylene or ultrahigh molecular weight polyethylene (for example, somarite (for example, somarite) that provides a stable friction coefficient with the stainless steel plate. Product name)) etc. are used.

3 Column beam frame, 10 braces,
10a 1st cut end (one member), 10b 2nd cut end (the other member),
20 friction damper, 20a friction damper, 20b friction damper,
30 Ball screw mechanism (motion conversion mechanism),
31 screw shaft part, 31b one end part, 32 connecting member,
33 Nut portion, 35 connecting member, 35a bearing,
40 frictional force generation mechanism, 40a frictional force generation mechanism,
41 flange part (rotational motion transmission member), 41a annular wall part, 41b rib part,
41h through hole,
42 rail (guide member), 42a guide surface,
42b rail (guide member), 42c guide surface,
43 Rotating inertial mass,
45 Spring member (second elastic member),
47 Spring member (first elastic member),
47a coil spring, 47b coil spring, 47c coil spring,
50 friction material, 60 sliding material,
70 pressure contact force changing mechanism,
71 hinge, 72 arm member,
73 Rotating inertia mass body, 74 Spring member,
75 Damping member, 77 Connecting member, 78 Spring member,
C31 axis (axial direction, center axis of rotation),
r turning radius, r0 turning radius, r1 turning radius,
L Lead length, V speed, G clearance

Claims (8)

A friction damper that is interposed between two members that move relative to each other and attenuates vibration between the two members,
A motion conversion mechanism that converts the reciprocating linear movement operation related to the relative movement into a reciprocating rotation operation about a predetermined axis;
A rotating inertial mass that is supported by one of the two members so as to be rotatable around the axis and is rotated by the rotating operation;
A friction material provided on the rotary inertia mass body and rotating integrally with the rotary inertia mass body;
A sliding material that is provided on the one member and that attenuates the vibration by a frictional force generated between the friction material and the friction material;
The friction damper according to claim 1, wherein the rotational speed of the friction material around the axis is increased by the motion conversion mechanism as compared with the speed of the linear movement operation. The friction damper according to claim 1,
Depending on the speed of the linear movement operation, the rotational speed of the rotating inertial mass changes,
A friction damper, comprising: a pressure contact force changing mechanism that increases or decreases a pressure contact force of the friction material against the sliding material in accordance with a magnitude of a centrifugal force acting on the rotary inertia mass body. The friction damper according to claim 1,
The rotary inertia mass body rotates around the axis, with a predetermined length relating to the linear movement operation as a lead length,
A friction damper having a rotation radius changing mechanism for increasing or decreasing the rotation radius of the rotary inertia mass body according to the speed of the linear movement operation. The friction damper according to claim 3, wherein
The friction damper according to claim 1, wherein the turning radius changing mechanism changes the turning radius of the rotating inertial mass body according to the magnitude of a centrifugal force acting on the rotating inertial mass body. The friction damper according to claim 4,
The motion conversion mechanism is provided with a rotational motion transmission member that is supported by the one member so as to be rotatable around the axis.
The rotary inertia mass body is rotatably supported by the one member via the rotary motion transmission member,
The rotating radius changing mechanism includes a guide member that allows relative movement in the rotational radius direction while restricting relative movement in the rotational direction of the rotary inertia mass body with respect to the rotational motion transmission member, and the rotary inertia mass body. A first elastic member for applying a centripetal force in the rotational radial direction to
The rotational motion is transmitted to the rotary inertia mass body by rotating the rotational motion transmission member based on the rotational motion converted from the linear movement motion by the motion conversion mechanism,
The friction damper according to claim 1, wherein the rotary inertia mass body moves to a position in the rotational radial direction where the centripetal force and the centrifugal force are balanced. The friction damper according to claim 5,
At least two of the rotary inertia mass bodies are provided,
The two rotary inertia mass bodies are arranged symmetrically with respect to the axial core. The friction damper according to claim 5 or 6,
The sliding material and the friction material are arranged to face each other in the axial direction,
A second elastic member for pressing the friction material against the sliding material is interposed between the friction material and the rotary inertia mass body;
The rotary inertia mass body is guided by the guide member so that the position outside the inner position in the radial direction of the rotation is pushed toward the sliding material or vice versa. This is a friction damper. The friction damper according to any one of claims 5 to 7,
The motion conversion mechanism has a ball screw mechanism in which a nut portion is screwed to a screw shaft portion via a ball-shaped rolling element,
The nut portion is supported by the one member of the two members while being restricted from moving in the axial direction while allowing rotation around the axial core.
The rotational motion transmitting member is rotatably supported by the one member via the nut portion,
The screw shaft portion is arranged with its axial direction along the direction of the linear movement operation, and one end portion of the screw shaft portion in the axial direction is fixed to the other member of the two members,
The friction damper according to claim 1, wherein the nut portion makes one rotation for each movement of the nut portion relative to the screw shaft portion by the lead length.