JPH0156204B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vibration control method for reducing low frequency vibrations of traffic bridges such as road bridges and railway bridges.

Generally, a traffic bridge has a structure in which a bridge 1 is supported at both ends by piers 2, as shown in FIG. In this type of traffic bridge, as the number of vehicles traveling on the bridge increases and the traveling speed increases, excessive external force is applied to the traffic bridge, and furthermore, as the distance between the piers increases, Coupled with the decrease in the bending rigidity of bridges, extremely large vibrations are induced in road bridges. Depending on the situation, such vibrations may generate air pressure vibrations due to bridge vibrations, which become low-frequency sound pressure waves, usually below 30 hertz, that propagate to the surrounding area, and may surface as so-called low-frequency pollution. . Furthermore, buildings that are close to each other due to vibration propagation to the ground,
Vibration can cause vibrations in homes, causing the shutters, glass doors, etc. to rattle, or the vibrations in the home itself can cause great discomfort to residents, causing vibration pollution.

Conventionally, countermeasures against the vibrations of traffic road bridges, which are the mechanism that generates noise and vibration pollution, have been made by reinforcing bridges and piers to increase their rigidity, or by adding auxiliary piers to increase the number of support points for bridges. Efforts were made to reduce the discomfort caused to residents by improving and changing the vibration characteristics of road bridges, and by installing soundproof walls, covers, etc. to insulate the low-frequency sound pressure itself that propagates into the atmosphere. .

However, the reality is that such conventional measures have not achieved sufficient vibration and noise reduction effects, and the use of land space is also difficult when installing auxiliary piers on existing traffic bridges or reinforcing bridges. They were often subject to physical constraints and had drawbacks such as construction problems.

The vibration reduction principle of the present invention is essentially different from the conventional measures described above, and it reduces the vibration itself of target structures such as traffic bridges (hereinafter referred to as target objects), thereby reducing vibration noise pollution. Active vibration control force is applied to the object at night when it is more noticeable, and passive vibration damping is applied during the day when the level of pollution is relatively low. This reduces operating costs and reduces the effects of low-frequency vibration pollution. It is an object of the present invention to provide a vibration control method that switches the vibration control system between large time periods and small time periods.

An embodiment of the present invention will be described below.
Figure 2 is a diagram showing the configuration of the vibration control device during the daytime, Figure 3 is a sectional view showing the electrodynamic actuator installed on a traffic road bridge and applying vibration control force, and Figure 4 is the vibration control device at night. A configuration diagram showing
FIG. 5 is a block diagram showing the difference in the structure of the vibration control device between daytime and nighttime. The configuration and operation of an embodiment of the present invention will be explained based on these figures. 1 is a bridge, 2 is a pier, and 3 is an electrodynamic actuator, the details of which are shown in FIG. 4a,
4b is between the bridge 1 and the electrodynamic actuator 3;
A support rod interposed between the electrodynamic actuator 3 and the fixed side, 5 a power receiving device that receives power from the electrodynamic actuator 3, 6 a load, and the power receiving device 5
Power is supplied from 31 is a coil holder, 3
2 is a drive coil wound around a coil holder 31;
33 is an excitation yoke facing the drive coil 32;
4 is a permanent magnet attached to the excitation yoke 33. The electrodynamic actuator 3 is configured as described above.

When an electric current is supplied to the drive coil of an electrodynamic actuator, an electromagnetic force is generated in the coil, and the electrodynamic actuator operates as an actuator (force generator). On the other hand, when the power is turned off and the drive coil is moved passively, a current is induced in the coil and it becomes a generator. The vibration control during the daytime is shown in FIG. 2, and its configuration and operation are as follows.

The movable drive coil 32 is attached to the bridge 1 by a support rod 4a.
It is fixed through. On the other hand, the excitation yoke 33 is fixed to the stationary side (ground) via a support rod 4b. The drive coil 32 is wound around the coil holder 31, and the end of the coil is electrically connected to the power receiving device 5. The drive coil 32 is attached to the excitation yoke 33 with a small gap therebetween. Power receiving device 5 connects electrical load 6 . Further, the magnetic flux Φ generated by the permanent magnet 34 interlinks with the drive coil 32 as shown by the broken line in FIG.

With the above configuration, when the bridge 1 receives an external force such as a vehicle or wind and induces vibration, the bridge 1 undergoes a bending vibration as shown by the broken line in the figure. Along with this, the drive coil 32 coupled to the bridge 1 vibrates. Since the drive coil 32 is mounted within the magnetic field generated by the permanent magnet 34, the drive coil 32
temporally cuts the interlinking magnetic flux Φ, thereby generating an induced electromotive force in the drive coil 32 based on electromagnetic induction. Since this induced electromotive force has a magnitude proportional to the vibration speed, it operates as a kind of passive electromagnetic damper, indirectly absorbing the vibration energy of the bridge 1 as electric energy,
This has the effect of suppressing the vibration of the bridge 1. Furthermore, the electromotive force of the drive coil 32 induced by the vibration of the bridge 1 is received by the power receiving device 5 and can be used for driving the electrical system or the electrical load 6, so that an energy saving effect can be obtained as well. , the power consumed to reduce the vibration of the bridge 1 is unnecessary. In this way, during the day, it operates as a passive electromagnetic damper,
Aiming to control vibrations on traffic bridges. Examples of the electrical load 6 include warning lamps and indicator lamps for traffic road bridges.

Next, the structure and operation of the nighttime vibration control device will be explained based on an embodiment shown in FIGS. 4 and 5. The mounting of the bridge 1 and the electrodynamic actuator 3 is the same as that shown in FIG. This system generates an electromagnetic force, and uses this electromagnetic force to actively reduce the vibration of the bridge 1. 7 is a sensor that detects the vibration speed of the bending vibration of the bridge 1; 8 is a control device; the control device 8 includes a preamplifier 81 that amplifies the vibration speed signal from the sensor 7; and control for improving the transmission characteristics of the signal. Excitation power supply 83 via circuit 82
The excitation power source 83 supplies an excitation current proportional to the vibration speed to the drive coil 32 of the electrodynamic actuator 3. With such a configuration, an electromagnetic force based on electromagnetic action is generated in the electrodynamic actuator 3, and this electromagnetic force is proportional to the vibration speed of the bridge 1, and is proportional to the vibration displacement of the bridge 1.
Since it has a phase difference of 90 degrees, it acts as a vibration reduction control force as a damping effect. At this time, electric power is required to reduce vibration.

The operation at this time is as follows.

First, the principle of vibration reduction is a forced force (external force) on the object.
When and control force act, m is the modal mass of the object, c is the damping coefficient, k is the object's spring constant, and F
It is assumed that the equation of motion is established where is an external force, U is a control force, and x is the displacement of the object. here,
For example, by detecting the vibration acceleration x¨ of the object, converting it into signals of velocity x and displacement x, and then applying these values to the above equation of motion, the optimal control force that can damp the external force F can be determined. U (i.e.
A control force proportional to the vibration speed of the object is obtained.

As can be seen from the above equation, the drive coil 32 of the electrodynamic actuator 3 is supplied with an excitation current corresponding to the vibration speed of the bridge 1.
The electromagnetic force generated acts on the bridge 1 as a control force, that is, a vibration damping force, which is proportional to the vibration speed. Vibration of the bridge 1 can be reduced by such a configuration.

Daytime/nighttime switching is done by a timer, but as shown in Figure 5, when the electrodynamic actuator is operated as a force generator, current is supplied to the coil from the excitation power supply, and when it is operated as a generator. is connected to a power receiving device (load) that receives the current induced in the coil. Therefore, the current flowing through the drive coil is controlled depending on whether the drive coil is connected to an excitation power source or a power receiving device.

From the above, during the day no current is supplied to the actuator and it acts as a generator, and at night it supplies current and acts as a force generator, and in response to bridge vibrations it acts as an active vibration control device. . The cause of vibration is the excitation force from a running vehicle, which occurs day and night. However, the degree to which it becomes a problem is different. At night, when vibration is a major problem, the electrodynamic actuator is operated as a force generator.
It will be used in the configuration of an active vibration control device.

As described above, as shown in the block diagram of Figure 5, by switching the vibration control system between daytime and nighttime, passive control is implemented during the daytime when the degree of vibration and noise pollution is relatively minor. In addition to reducing the vibration caused by force and eliminating the power consumption of the device, the control system can be switched to proactively apply control force at night, when residents can sleep and feel uncomfortable. The purpose is to reduce vibrations on traffic bridges and ensure a comfortable living environment.

In the above embodiment, an example has been described in which the system is switched to a passive system during the day and an active system at night, but it goes without saying that depending on the situation, it is possible to reverse these time periods.

The above example uses a traffic bridge, but it can also be used to suppress vibrations in towers, buildings, antennas, etc.

According to the invention described above, efficient vibration control and power saving can be achieved by switching between the passive system and the active system depending on the time of day.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing a traffic bridge, FIG. 2 is a configuration diagram showing a daytime control system for implementing the method of an embodiment of the present invention, and FIG. 3 is an electrodynamic actuator shown in FIG. 2. 4 is a block diagram showing a nighttime control system for implementing the method of one embodiment of the present invention, and FIG. 5 is a control system for implementing the method of one embodiment of the present invention. FIG. DESCRIPTION OF SYMBOLS 1... Bridge, 2... Pier, 3... Electrodynamic actuator, 4a, 4b... Connecting rod, 5... Power receiving device, 6... Electric load, 7... Sensor, 8... Control device, 31 ... Coil holder, 32 ... Drive coil, 33 ... Excitation yoke, 34 ... Permanent magnet, 8
1... Preamplifier, 82... Control circuit, 83...
Excitation power source: In the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A detection means for detecting the amount of vibration of a vibrating body that vibrates in response to an external force, and an electrodynamic actuator that is attached to the vibrating body and generates a control force corresponding to the amount of vibration detected by the detection means. In preparation, during times when the influence of low-frequency vibration pollution caused by the vibration of the vibrating body is large, the amount of vibration of the vibrating body is detected by the detection means attached to the vibrating body, and the control force corresponding to this vibration amount is applied to the A vibration control method, characterized in that the electrodynamic actuator is caused to generate vibrations in an electrodynamic actuator, and during a time period different from the above-mentioned time period, the electrodynamic actuator is operated as an electromagnetic damper and switched to apply a passive control force.