JP2607377B2 - Exciter for structural test - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a vibration exciter used for testing large structures and the like, which can change a vibration force during rotation and a vibration direction freely. In addition, the driving force can be reduced.

[Conventional technology]

Vibration tests are often performed to examine the effects of various structures such as large bridges and high-rise buildings due to earthquakes.

There are various vibration methods for performing such a vibration test. For example, vehicle running, pendulum vibration method, rocket injection vibration method, explosive explosion, human power vibration method, exciter vibration method, etc. are used. From the viewpoint of data reliability, it is optimal to use a forced excitation method using an exciter.

On the other hand, when trying to vibrate a large structure, a large vibrating force is required, and the driving force of the exciter becomes enormous.

Therefore, in order to reduce the driving force, the piston rod of the air cylinder is connected to the weight attached to the crankshaft, and the self-weight of the weight is offset by the compressed air in the cylinder to reduce the driving force. There is.

[Problems to be solved by the invention]

However, in the conventional exciter, since the exciting force is obtained by the inertial force of the reciprocating motion of the weight attached to the crankshaft, if the reciprocating motion direction of the weight is determined by the exciter, the other There is a problem that it is not possible to vibrate in the direction of.

In addition, it is difficult to increase or decrease the reciprocating weight during the operation, and there is a problem that the exciting force cannot be changed during the operation.

Furthermore, when the driving force is reduced by using an air cylinder, if the pressure is constantly adjusted to balance the own weight of the initial weight, the balance will be lost when the excitation force is changed by increasing or decreasing the weight, and the driving force will be lost. There is a problem that a case where the reduction is not achieved occurs.

The present invention has been made in view of such prior art,
It is an object of the present invention to provide a structural test exciter that can be excited with a small driving force, can freely select an exciting direction, and can change the exciting force during operation.

[Means for solving the problem]

In order to solve the above problems, the present invention provides two rotary drive shafts arranged in parallel so as to be able to change the phase of each other so that the vibration direction can be changed, and adjusts the radius of rotation to each rotary drive shaft. Attaching a weight to generate a vibrating force by centrifugal force as much as possible, while connecting the piston rod of a fluid balancing cylinder for load balancing provided swingably to the end of these rotary drive shafts via a rotary arm, It is characterized in that a pressure adjusting cylinder is provided which can be connected to these load balancing fluid pressure cylinders to adjust the pressure in the fluid pressure cylinders and reduce the driving force.

[Action]

Weights are eccentrically attached to the two rotary drive shafts arranged in parallel, and weights are attached. These are synchronously inverted to vibrate using the centrifugal force generated by the unbalanced moment. By balancing the forces, the exciting force can be taken out in any direction. Further, by changing the amount of eccentricity of the diet, the exciting force can be changed even during operation. Further, by changing the phase of the weight, it is possible to vibrate not only vertically but also horizontally.

〔Example〕

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIGS. 1 (A) and 1 (B) and FIGS. 2 (A) and 2 (B) are a plan view and a front view, respectively, of an embodiment of a structural test vibration exciter according to the present invention.

Usually, two vibration exciters are used for the structural test, and are composed of a reference machine and a follower. The reference machine and the follower have substantially the same configuration. First, the reference machine will be described.

This reference machine has two rotary drive shafts 1 and 2,
Weights 3 and 4 are respectively attached to the tips. These weights 3 and 4 can be attached to the rotary drive shafts 1 and 2 in the radial direction, so that the rotary drive shafts 1 and 2 are provided with rectangular sliders 5 and 6. Weights 3 and 4 are fitted to the sliders 5 and 6, respectively. Then, feed screw mechanisms 7, 8 are provided between the weights 3, 4 and the sliders 5, 6, and the weights 3, 4 can be moved by rotating the feed screw.

In order to rotate these rotary drive shafts 1 and 2 in opposite directions at a synchronous speed, bevel gears 9 and 10 are attached to the ends of the rotary drive shafts 1 and 2.
Are attached, and mesh with bevel gears 13 and 14 at both ends of a main shaft 12 driven by a driving synchronous motor 11. When the rotary drive shaft is rotated in this state, relative movement occurs between the weights 3, 4 and the sliders 5, 6, and the weights 3, 4 move. Bevel gears 17,18
The bevel gears 19 and 20 meshing with the shafts are mounted on the operation shafts 21 and 22 through the hollow portions of the rotary drive shafts 1 and 2. The other ends of these operating shafts 21 and 22 have bevel gears 23 and 24
Are attached, are driven to rotate via the main shaft 12, and mesh with bevel gears 27, 28 attached to both ends of a moment changing shaft 26 which is rotated via a differential gear device 25. It rotates in the same direction at the same speed as 1,2.

Next, in order to operate only the feed screws 15 and 16 during rotation, the worm wheel 30 is mounted on the outer periphery of the carrier 29 of the differential gear device 25.
Are mounted, and a worm 32 which is rotationally driven by an unbalanced moment changing motor 31 is engaged. Therefore, when the unbalanced moment changing electric motor 31 is rotated, the carrier 29 of the differential gear device 25 is rotated to cause a differential, and the rotation speed of the moment changing shaft 26 is changed, so that the feed screws 15, 16
Turns, and the weights 3 and 4 are moved.

In order to reduce the rotational driving force of the weights 3 and 4, crank arms 33 and 34 are attached to ends of the rotational drive shafts 1 and 2 and are swingably attached via connecting rods 35 and 36. Piston rods 39, of load balancing cylinders 37, 38
Connected to 40. The load balancing cylinders 37 and 38 are opposed to each other in the horizontal direction, and a pressure adjusting cylinder 41 is attached to communicate with both cylinder chambers.

The piston rod 42 of the pressure adjusting cylinder 41 includes:
The feed nut of the feed screw mechanism 43 is attached, and the feed screw is connected to the worm 32 of the differential gear device 25 driven by the motor 31 for changing the unbalanced moment.

Therefore, when the feed screw is rotated, the volume of the pressure adjusting cylinder 41 changes, and the load balancing cylinders 37, 3
The pressure inside 8 can be changed.

The pressure of the load balancing cylinders 37 and 38 performed using such a pressure adjusting cylinder 41 is determined as follows.

As shown in FIG. 3, the pressure of the load balancing cylinders 37 and 38 is set to P ₀ , based on the balance at the maximum excitation moment Mmax.
Assuming that the volume is V ₀ , the position X of the piston of the pressure adjusting cylinder 41 at an arbitrary excitation moment M is obtained.

F = M / 2r P _G0 = Mmax / 2A ₁ r P _G1 = M / 2A ₁ r Boyle's law; from P ₀ V ₀ = P ₁ V ₁ to (Mmax / 2A ₁ r + 1) (A ₁ l ₀ + A ₂ L _0/2 ) = (M / 2A ₁ r + 1)
_{{(A 1 l 0 + A} 2/2 (L 0 + X)} X = 1 / A 2 {(Mmax + 2A 1 r) (2A 1 l 0 + A 2 L 0) / (M + 2A 1
r) −2A ₁ l ₀ ｝ −L _{0 By} controlling the position of the pressure adjusting cylinder 41 to be the position X thus obtained, the driving torque can be reduced.

This position X is shown by a dashed line in FIG. Therefore, when the excitation force is changed, the driving torque can be ideally reduced by moving the piston of the pressure adjusting cylinder 41 along the curve of X, but it is a non-linear curve and the control system Because of the complexity, the control may be performed by approximating a straight line as shown in FIG. 4, for example, and the torque required for driving in this case is shown in FIGS. 5 (A) and 5 (B). As is clear from these, the maximum excitation moment
It can be seen that the driving torque can be reduced even in the case of Mmax or when the excitation moment is set to 0. Also, in the case where the excitation moment is changed between Mmax and 0, although not shown, the driving tongue can be similarly reduced.

Next, the follower will be described in brief with reference to FIGS. 2A and 2B. The driving force of the drive synchronous motor 11 is changed so that the phase of the weights 3 and 4 can be changed with respect to the reference machine. The input is made via the changing differential gear unit 44. That is, the driving force is input from the driving synchronous motor 11 to the phase changing differential gear device 44, and the driving force is transmitted from the output side to the main shaft 12 via the gear. A worm wheel 45 is attached to the carrier of the phase change differential gear device 44 so that the worm wheel 45 driven by the phase change motor 46 can change the phase of the weights 3, 4 with respect to the reference machine. Has become. Since the other configuration is the same as that of the reference device, the same reference numeral is marked and the description is omitted.

The vibration test for a structural test having such a configuration is performed as follows.

First, when the vibration is applied in the vertical direction, as shown in FIG. 6 (A), the two weights 3 and 4 of the reference machine are brought into a state where their respective centers of gravity approach each other in the horizontal direction, and the weight of the following machine is adjusted. The centers of gravity of the two weights 3 and 4 are separated from each other in the horizontal direction, and the rotations of the reference machine and the follower are synchronized in opposite directions.

Then, when each of the rotary drive shafts 1 and 2 rotates 90 degrees, the weight
3 and 4 are all located above, and a vibrating force is generated upward. Further, when rotated by 180 degrees, the exciting force is canceled and no exciting force is generated in any direction. Further, when rotated 270 degrees, all the weights 3 and 4 are located below, and a downward exciting force is generated.

Next, when performing torsional vibration, as shown in FIG. 6B, the center of gravity of the weights 3 and 4 of the follower is set in the horizontal direction in the same manner as the center of gravity of the weights 3 and 4 of the reference machine. The initial state is set to the state approached by and the synchronous rotation is performed in the opposite directions.

Then, when rotated by 90 degrees, the exciting force of the reference machine is generated upward, and the exciting force of the following machine is generated downward. Further, when rotated by 180 degrees, the positions of the centers of gravity of all the weights 3 and 4 are located apart from each other in the horizontal direction, and no exciting force is generated. In addition, 27
When rotated by 0 degrees, the excitation force of the reference machine is generated downward, and the excitation force of the follower machine is generated upward. The excitation force is generated in the opposite direction to the case of 90 degrees, and the torsional vibration is performed.

Further, in the case of vibrating horizontally, FIG. 6 (C)
As shown in, the center of gravity of all the unbalanced weights 3 and 4 of the reference machine and the follower are located in one horizontal right direction,
They rotate synchronously in opposite directions.

Then, at 0 degree (initial position), a vibration force to the right in the horizontal direction is generated. At 90 degrees and 270 degrees, no vibration force is generated, and at 180 degrees, all the weights 3, 4 move to the left side in the horizontal direction. Position, and an exciting force to the left is generated.

In this way, by using the reference machine and the follower and changing the phases of the weights 3 and 4, the phase and the exciting direction of the exciting force of the reference machine and the follower can be easily changed from the vertical direction to the torsional excitation. be able to. In this case, the phases of the weights 3 and 4 can be easily changed during operation by using the differential gear device 45. Further, when the vibration direction is changed in the horizontal direction, the phase can be changed during stoppage by using the phase change flanges 48 and 49.

On the other hand, when the excitation force is changed, the respective unbalanced moment changing motors 31 are started and the moment changing axes are changed.
By rotating the feed screws 15 and 16 via 26 and moving the weights 3 and 4, the radius of rotation up to the center of gravity can be changed, and the exciting force due to centrifugal force can be changed. Then, since the feed screw of the feed screw mechanism 43 for pressure adjustment is rotated at the same time as the change of the excitation force, the piston of the cylinder 41 for pressure adjustment is moved by a predetermined amount to reduce the driving force.

Therefore, the exciting force can be changed even during driving, and the driving force can be reduced with the change in the exciting force.

In the above embodiment, the feed screw mechanism is used to change the radius of rotation up to the center of gravity of the weight. However, the present invention is not limited to this, and another mechanism may be used. Further, the differential gear device and the slider are used as the mechanism for changing the phase, but another mechanism may be used. Further, the method of moving the piston of the pressure adjusting cylinder is not limited to the feed screw, but may be another mechanism. Further, the method of controlling the pressure adjusting cylinder is not limited to the case where an approximate expression using a straight line is used, but a theoretical expression or another approximate expression may be used.
Further, the load balancing cylinder and the pressure adjusting cylinder are not limited to air cylinders, but may be cylinders using other gases.

〔The invention's effect〕

As described above in detail with one embodiment, according to the structural test vibration exciter of the present invention, it is possible to vibrate by centrifugal force, and to take out the vibrating force directly from the rotary drive shaft. It has the following advantages over the conventional exciter using inertial force.

By changing the mounting position of the weight with respect to the rotary drive shaft, the radius of rotation up to the center of gravity of the weight changes, and the exciting force due to centrifugal force can be changed, making it easy to change the exciting force even during rotation. Can be.

By changing the phase of the rotary drive shaft, the vibration direction can be arbitrarily changed between the vertical direction, the torsional vibration, and the horizontal direction.

The drive force is reduced by the load balancing fluid pressure cylinder and pressure adjustment cylinder, so even when the excitation force is changed, the pressure in the fluid pressure cylinder can be automatically changed, and the excitation force can be reduced. The driving force can be reduced regardless of the size.

[Brief description of the drawings]

FIGS. 1 (A) and 1 (B), and FIGS. 2 (A) and 2 (B) relate to an embodiment of a structural test vibration exciter according to the present invention.
FIG. 3 is a plan view, each figure (B) is a front view, FIG. 3 is an explanatory view of the control of the position of the piston of the pressure adjusting cylinder, FIG. 4 is an explanatory view of a control curve of the position of the pressure adjusting cylinder, FIG. FIGS. 7A and 7B are explanatory diagrams of the reduced driving torque, and FIG.
(A), (B), and (C) are illustrations of the phase of the unbalanced weight and the vibration direction. 1,2 ... Rotating drive shaft, 3,4 ... Weight, 7,8 ... Feed screw mechanism, 11 ... Synchronous motor for driving, 12 ... Spindle, 25 ... Differential gear device, 26 ... Moment Change axis, 31… Motor for changing unbalanced moment, 37,38… Cylinder for load balancing, 41… Cylinder for pressure adjustment, 43… Feed screw mechanism,
44 …… Phase changing differential gear device, 46 …… Phase changing motor, 48,49 …… Phase changing flange.

Claims (1)

(57) [Claims] 1. A rotary drive shaft arranged in parallel so that the phase of each rotary drive shaft can be changed so as to be able to change the vibration direction, and a rotational radius can be adjusted to each of the rotary drive shafts by centrifugal force. A weight for generating a vibration force is attached, and a piston rod of a load-balancing fluid pressure cylinder, which is swingably provided, is connected to the ends of these rotary drive shafts via a rotary arm. A structural test vibration exciter comprising a pressure adjusting cylinder connected to a pressure cylinder and capable of adjusting the pressure in the fluid pressure cylinder to reduce the driving force.