GB2205921A

GB2205921A - A vibration damping apparatus

Info

Publication number: GB2205921A
Application number: GB08812656A
Authority: GB
Inventors: Kiyoyasu Mitsumori; Masayuki Shigeta; Tadashi Shibata; Masaharu Uhno; Masatoshi Ohta
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 1987-06-03
Filing date: 1988-05-27
Publication date: 1988-12-21
Anticipated expiration: 2008-05-27
Also published as: CN1007286B; JPS63306183A; GB2205921B; CN88103366A; GB8812656D0

Abstract

A vibration damping apparatus is disclosed which may prevent vibration from a vibrating body (5) to a vibrated body (3A). The vibration propagated to the vibrated body detected by a vibration detector (16). On the basis of the detected vibration, an electromagent (11) is operated so that the vibrated body (3A) is vibrated in a direction in which the propagated vibration is suppressed. <IMAGE>

Description

"A vibration damping apparatus" The present invention relates to a vibration damping apparatus for suppressing propagation of vibration from a "vibrating body", which is subjected to an outside force, to a "vibrated body" which is supported by the vibrating body.

As shown in, for example, Japanese Patent Unexamined Publication No. 60-106769, there is proposed a vibration damping apparatus for suppressing propagation of vibration from a "vibrating body" subjected to an outside force to a "vibrated body", in which the vibration of the vibrated body is detected and a damping counterweight provided in the vibrated body is vibrated so as to cancel or offset the resultant vibration.

However, such a method would be available for a specific frequency but it is necessary to prepare a plurality of damping counterweights of equivalent masses that are different from each other for the composite vibration composed of components having a plurality of frequencies and to apply vibrations to the respective counterweights. Also, the damping counterweights to be vibrated and their guide means may require relatively large spaces.

A primary object of the invention is to provide a vibration damping apparatus which may rapidly correspond to the vibration having any frequency.

Another object of the invention is to provide a vibration damping apparatus which save its installation space.

In order to attain these or other objects, according to the present invention there is provided a vibration damping apparatus comprising an electromagnet and an elastic member juxtaposed between a vibrating body and a vibrated body, a vibration detector provided in the vibrated body, and a controller for controlling a phase of a signal waveform and an amplitude of vibration on the basis of the detected signal of the vibration detector to energize the electromagnet.

In such an arrangement, since the electromagnet and the elastic member are juxtaposed, if the vibrated body is vibrated, its vibration causes a space of the electromagnet to be changed in a direction in which the vibration is smaller. As a result, the propagation of vibration to the vibrated body is prevented. In this case, since the force for changing the space between the electromagnet and an armature is controlled by the applied voltage (since the attractive force of the electromagnet depends upon the current and the number of turns of coils, it is proportional to the voltage at a constant frequency), the apparatus is rapidly responsible to any frequency.

Furthermore, since the electromagnet and the elastic member may be disposed in a narrow space between the vibrating body and vibrated body, there is no need to provide a large installation space.

The present invention will now be described in greater detail by way of examples with reference to the accompanying drawings, wherein: Fig. 1 is a schemativ view showing a state in which a vibration damping apparatus according to the invention is applied to an elevator; Fig. 2 is an enlarged cross-sectional view showing a part P in Fig. 1; Fig. 3 is a graph showing a change of a gap of an electromagnet; and Figs. 4 to 6 are cross-sectional view showing vibration damping apparatuses according to other embodiments of the invention.

One embodiment of the invention will now be described with reference to Figs. 1 to 3 which show a state in which a vibration damping apparatus according to the present invention is applied to a connecting portion between a cage frame of an elevator and a suspension rope. The apparatus will be described in more detail. A cage 1 of the elevator is supported by a rectangular lower beam 3B of a cage frame 3 through damping rubber 2. Vertical columns 4A and 4B are provided to both sides of the lower beam 3B.

On the upper ends of the columns 4A and 4B, there is provided an upper beam 3A. A suspension rope 6 is connected at one end to the upper beam 3A through a suspension plate 5. A counterweight 7 is connected to the other end of the rope 6. The suspension rope 6 is wounded around a drive sheave 8 of a winder and a displacement sheave 9 in a well bucket manner. The suspension plate 5 is engaged with the upper beam 3A through a support unit 10. The support unit 10 is substantially composed of an iron core 12 made of permanent magnet and incorporating therein a coil 11 wound in a flat annular shape and an armature 13.

The iron core 12 is fixed to the upper beam 3A, and the confronted armature 13 is fixed to the suspension plate 5. The iron core 12 has a magnetic electrode 12P located in the center of the coil 11. The armature 13 has a magnetic electorde 14 confronted through a gap T with the electrode 12P at the center of the coil 11. The iron core 12 has a lower portion 12E that surrounds a lower portion of the coil 11 and faces a circumferential surface of the magnetic electrode 14. A rubber 15 is interposed between the lower portion 12E and the armature 13. A vibration detector 16 is mounted on the upper beam 3A in the vicinity of the thus constructed support unit 10.

A controller 17 connected to an electric power supply source (not shown) is provided in the cage 1. The controller 17 is so constructed as to energize the coil 11 on the detection signal of the vibration detector 16. The controller 17 is not necessarily provided within the cage 1 but may be provided in an operator room (not shown).

In the above-described arrangement, when the elevator is operated, the vibration propagated to the suspension rope 6 through the drive sheave 8 causes the suspension plate 5 to vibrate. The suspension plate 5 serves as a vibrating plate and propagates the vibration to the vibrated body, i.e., cage frame 3. The propagated vibration is detected by the vibration detector 16 on the upper beam 3A.

On the basis of the detected signal, the controller 17 controls a phase of a signal waveform and an amplitude of vibration to energize the coil 11 of the electromagnet so that the detected signal will become small. It should be noted that the gap T between the magnetic electrode 12P of the iron core 12 and the magnetic electrode 14 of the armature 13 is maintained by a thickness of the rubber 15 interposed between the iron core 12 and the armature 13. Therefore, by changing the applied voltage, it is possible to change the gap T to thereby generate vibration for reducing the propagated vibration.

The change of the gap T by the rubber 15 will be described in detail. Assume that the suspension plate 5 (vibrating body) is subjected to a force in the direction in which it is to be raised, the upper beam 3A (vibrated body) is subjected to a downward force by the gravitational force of the cage 1. As a result, the rubber 15 is compressed so that the gap T is determined. However, since the iron core 12 is formed of the permanent magnet, the attractive force between the magnetic electrode 14 of the armature 13 and the permanent magnet causes the gap T to be reduced by AT (actually the rubber 15 is compressed as expressed by T - AT). Under such a condition, when the coil 11 is energized on the basis of the signal of the controller 17, as shown in Fig. 3, the change c in the gap in the vertical direction is produced with reference to the compression b of the rubber 15 by the attractive force of the permanent magnet while the rubber 15 is further compressed by AT relative to the compression a of the rubber 15 only due to the cage gravity. Incidentally, it is sufficient that the compression amount AT of the rubber 15 due to the permanent magnet be set at an initial stage in correspondence with the amplitude of the propagated vibration.

As described above, according to the foregoing embodiment, the electromagnet is energized in response to the detected vibration so as to repeatedly compress the rubber 15 and release the compression.

It is therefore possible to rapidly absorb the vibration in response to a plurality of composite frequencies. At the same time, since there is no need to provide damper counterweights or their guide means as in the conventional system, a large installation space is not needed in the system according to the present invention. Also, as shown in Fig. 2, since the coil 11, the iron core 12, the armature 13 and the rubber 15 are arranged around the magnetic electrodes 12P and 14, these components may be formed in a unit and the installation space there for may be saved.

In the foregoing embodiment, the iron core 12 is made of permanent magnet, but instead of the permanent magnet, it is possible to construct the system so that coils other than the coil 11 are always energized.

Fig. 4 shows an embodiment in which the propagation of the vibration and the effect to damp the vibration are the same as in the foregoing embodiment but the electromagnet 21 and the elastic member 20 are separated from each other. For example, in the case that a support 18 which needs the vibration damping effect like a vibration preventing base for an electronic microscope is installed on a floor 19 of a building, the elastic member 20 such as a vibration preventing rubber is interposed between the components 18 and 19. In such a case, it is unnecessary to further interpose a rubber between the iron core 23 and the armature 24 constituting the electromagnet 21.By the attractive force between the iron core 23 and the armature 24 due to the energization of the coil 22, the elastic member 20 is compressed or released from the compression to thereby absorb the vibration propagated from the floor 19. Also, in the case of an elevator, instead of the damping rubber 2a shown in Fig. 1, the electromagnets 21 may be interchanged by the elastic members 20.

Fig. 5 shows a case where a rod 25 is adpated to pass through a central portion of an electromagnet 26. For example, the rod 25 may be a simple rod connected to suspension rope end of the elevator, and the vibrated body 24 corresponds to the upper beam of the cage frame. In this case, the rod 25 has a hole 28H in its central portion. The iron core 28 on which a coil 27 disposed coaxially to the rod 25 is mounted is provided on the vibrated rod 24. An armature 29 is arranged through a rubber 30 along the longitudinal direction of the rod 25a with respect to the iron core 28. The electromagnet 26 is thus formed by those compornents 27, 28, 29. The above-described iron core 28 surrounds an inner circumferential wall and the upper and lower ends of the coil 27. Thus, a magnetic electrode 28P is formed by a part partially surrounding the outer circumferential wall of the coil 27.On the other hand, the armature 29 has centrally a hole 29H through which the above-described rod 25 passes. The armature 29 has a magnetic electrode 29P which confronts the magnetic electrode 28P and partially surrounds the outer wall of the coil 27. A nut B is threadedly engaged with an end portion of the rod 25 passing through the armature 29 to thereby engage the rod 25 with the armature 29. If necessary, it is possible to enhance the damping effect by interposing the elastic member between the nut B and the armature 29. In such an arrangement, the coil 27 is energized in response to the detected vibration, so that the rubber 30 is compressed or released to thereby dampen the propagation of the vibration from the rod 25 to the vibrated body 24.

Fig. 6 shows an embodiment in which the damping unit shown in Fig. 5 is applied to the suspension plate 5 shown in Fig. 1. The electromagnet 26 is located below the suspension plate 5. Below the suspension plate 5, a nut B is screwed into an end of the simple rod 25 through a first elastic body 32 and a seat 31. Then, a second elastic member 33 is also interposed between the suspension plate 5 and the upper beam 3A. With such an arrangement, since the vibration propagated from the simple rod 25 is damped by the first elastic member 32 and the electric magnet 26 to be transmitted to the suspension plate 5 but is further damped by the second elastic member 33, the vibration propagated to the upper beam 3A is negligible.

Although the foregoing description is concerned with the application to the elevator or the electronic microscope, it is apparant that the invention may be applied to a support for supporting a member that dislikes the vibration as in a semiconductor producing apparatus, for example.

As has been described above, by repeatedly compressing or releasing the rubber member in accordance with the energization of the electromagnet in response to the detected vibration, the body to be vibrated is vibrated in an opposite direction to the propagated vibration. It is, therefore, possible to rapidly absorb any kind of vibration. Also, since the damping unit may be located in the vicinity of the damper device such as damping rubber, there is no need to provide a large space for installation of the system.

Claims

1. A vibration damping apparatus comprising: an elastic member interposed between a vibrating body and a vibrated body; an electromagnet, provided on one of said vibrating body and said vibrated body, for producing a force to change a space between said vibrating body and said vibrated body; an armature, provided on the other of said vibrating body and said vibrated body, for confronting with said electromagnet; a vibration detector provided on said vibrated body; and a controller for controlling a phase of a signal waveform and an amplitude of vibration on the basis of a detection signal outputted from said vibration detector, thereby energizing said electromagnet.

2. The vibration damping apparatus according to claim 1, wherein said vibrating body comprises a suspension rope of an elevator, and said vibrated body comprises a cage of said elevator.

3. The vibration damping apparatus according to claim 1, wherein said vibrating body comprises a suspension plate engaged with one end of a suspension rope of an elevator, and said vibrated body comprises an upper beam that forms a suspension frame for supporting a cage of said elevator.

4. The vibration damping apparatus according to claim 1, wherein said vibrating body comprises a lower beam that forms a suspension frame for supporting a cage of an elevator.

5. The vibration damping apparatus according to claim 1, wherein said electromagnet comprises an iron core and an armature, and at least one of said iron core and said armature is composed of permanent magnet.

6. The vibration damping apparatus according to claim 1, wherein said electromagnet is adapted to be always energized to compress said elastic member.

7. The vibration damping apparatus according to claim 1, wherein said vibrating body comprises a floor of a building, and said vibrated body comprises a vibration preventing base of an electronic microscope.

8. The vibration damping apparatus according to claim 1, wherein said vibrating body comprises a floor of a building, and said vibrated body comprises a semiconductor producing machine.

9. A vibration damping apparatus constructed substantially as herein described in the accompanying drawings.