JPH075308Y2 - Magnetic fluid damper - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a magnetic fluid damper capable of adjusting a damping constant by combining a magnetic fluid and a magnet.

2. Description of the Related Art Conventionally, in precision instruments, measuring instruments, and buildings, a method of absorbing and damping vibrations by incorporating it into the lower end of the device is generally adopted. Such a vibration isolation table or the like is generally composed of a vibration isolation device made of air-filled rubber.

However, with such a rubber vibration isolator, vibrations of several tens of hertz or more can be largely damped, but almost no vibrations of less than several tens of hertz, for example, 3 hertz or less can be absorbed and damped.

Therefore, conventionally, as shown in FIG. 1, it has been proposed to combine a magnetic fluid damper 2 in parallel with a rubber vibration isolator 1 to absorb and damp mechanical vibration.

As shown in FIG. 2, a damper 2 using this magnetic fluid is obtained by alternately stacking magnetic bodies 6 made of permanent magnets and having adjacent poles having the same pole in a cylindrical container 4 made of a non-magnetic body. It is configured. Reference numeral 7 denotes a magnetic fluid in which magnetic particles such as magnetite or ferrite are uniformly dispersed in various solvents such as water, kerosene, various hydrocarbons, etc., and is enclosed in a gap between the cylindrical container 4 and the magnetic body 6. In this case, the inner diameter of the container 4 and the outer diameter of the magnetic body 6 are extremely precisely finished to obtain desired characteristics. Since the magnetic fluid 7 is a viscous fluid itself, when a flow occurs in the magnetic fluid 7 in the gap between the cylindrical container 4 and the magnetic body 6 due to the vibration of the shaft 8 like a general oil damper, its own viscous resistance. As a result, a braking force acts on the shaft 8. Also, as the properties of magnetic fluid,
Since the apparent viscosity changes due to the change of the external magnetic field, the magnetic field of the magnetic body 6 increases the viscosity of the magnetic fluid 7 to adjust the damping constant, and the shaft 8 formed continuously on the vibration-isolated object 5 is adjusted. It is designed to absorb and attenuate the applied low-frequency mechanical vibration.

By the way, when the members and the structure of these magnetic fluid dampers 2 are determined, the absorption and damping characteristics of the vibration are uniquely determined. Therefore, when the weight of the whole body is changed, for example, when the weight of the vibration-isolated object 5 is changed to improve the vibration-isolated object 5, the magnetic fluid 7 is added between the lower portion of the magnetic body 6 and the lower portion of the non-magnetic container 4. The pressure becomes larger than the set pressure, the velocity of the magnetic fluid flowing through the gap formed by the outer diameter of the magnetic body 6 and the inner diameter of the container 4 increases, and the damper function changes. Therefore, the damping constant of the magnetic fluid damper is changed. In order to keep it constant, it must be changed according to its weight. As a result, the efficiency of the correction work is deteriorated and the structure of the magnetic fluid damper is complicated, resulting in the drawback that the magnetic fluid damper of this kind cannot be supplied at a low cost.

In view of this point, the present invention provides a communication pipe having a wider flow path than the gap between the magnetic container and the cylindrical container in which the valve for magnetic fluid control is installed between the upper part and the lower part of the container.
The main purpose is to propose a magnetic fluid damper that eliminates the above-mentioned drawbacks by allowing the damping constant of mechanical vibration to be adjusted to a constant value by freely changing and setting the flow of magnetic fluid according to the weight change of the object to be isolated. To do.

An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 3 is a sectional view showing an embodiment of the present invention, and the same parts as those shown in FIG. 2 are designated by the same reference numerals. The magnetic bodies 6 are arranged so as to repel each other, and
It is stored with a gap so that it does not touch the periphery of 11. A magnetic fluid 13 is filled and sealed in the gap between the container 11 and the magnetic body 6.

Reference numeral 10 denotes a communication tube, which is provided for communicating the magnetic fluid 13 between the lower portion 11a and the upper portion 11b of the magnetically-contained container 11. For example, when the inner diameter of the cylindrical container 4 is 30.2 mm and the outer diameter of the magnetic body 6 is 30.0 mm, the inner diameter of the communication pipe 10 is 6 mm, and the cross-sectional area of the magnetic fluid 13 is the gap between the cylindrical container 4 and the magnetic body 6. Is set larger than the cross-sectional area of the magnetic fluid so that the flow of the magnetic fluid due to the pressure fluctuation mainly acts on the communication pipe 10 side.

Further, the magnetic fluid 13 caused by the vibration of the vibration-isolated object in the container 11
The flow rate of the magnetic fluid due to the pressure fluctuation is finely adjusted by the valve 14 provided in the middle of the communication pipe 10 so that the flow rate can be freely finely adjusted.

Therefore, when the weight of the object to be vibration-isolated in the initial setting stage is changed after that and the pressure of the magnetic fluid is changed, the magnetic body 6 connected to the object-to-be-vibrated via the shaft 8 and the magnetic body 6 are connected. The magnetic fluid 13 is moved to the bottom of the magnetic body 6 due to the downward pressure applied to the plurality of magnetic bodies 6 stacked with the adjacent poles as the same pole so as to repel each other. It is diverted to the side of the communication pipe 10 where the pressure is low. In this case, since the apparent viscosity of the magnetic fluid 13 in the gap between the cylindrical container 4 and the magnetic body 6 is high and the viscous resistance is substantially large, the apparent viscous resistance of the magnetic fluid 13 is increased. It will flow to the side of the communication pipe 10 that does not work. The magnetic fluid 13 that has flowed into the communication pipe 10 has no apparent viscosity and thus has a low viscosity, and does not act as a damper as it is. Therefore, the flow cross-sectional area of the magnetic fluid can be corrected by finely adjusting the valve 14, and the change in the damper constant due to the change in weight can be corrected to the set damper constant. Will also keep the damping constant set constant.

As described above, according to the present invention, a plurality of magnetic bodies connected to an object to be isolated via a shaft and a plurality of magnetic poles, which are adjacent to each other so as to repel each other including the magnetic body, are formed as the same pole. The magnetic body of the above-mentioned magnetic body is housed in a non-magnetic container with a gap so that the periphery of the magnetic body does not contact the inner wall of the non-magnetic container, and between the container and the magnetic body and between the laminated magnetic bodies. In the magnetic fluid damper in which the gap is filled with magnetic fluid so as to be tightly contained, the non-magnetic container is provided with a communication pipe for communicating the upper part and the lower part thereof, and a flow rate control valve is provided in the middle of the communication pipe. Even if the weight of the vibration-isolated object is changed at any time, a constant damper effect can be obtained. Although the conventional hydraulic damper has a complicated structure and requires a large number of parts and manufacturing steps, the present invention is simplified in its entirety, and therefore the damper function in the low frequency region of several tens Hz or less can be achieved with a simple configuration. Can be achieved.

[Brief description of drawings]

FIG. 1 is a view showing an example of a conventional device of this kind, FIG. 2 is a cross-sectional view showing the same detailed structure, and FIG. 3 is a cross-sectional view showing an embodiment of the present invention. 6 ... Magnetic substance, 10 ... Communication pipe, 11 ... Magnetic container, 11a ... Lower part of container, 11b ... Upper part of container, 13 ... Magnetic fluid, 14 ... Valve.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-57-69136 (JP, A) JP-A-55-63029 (JP, A) Jikken 41-1858 (JP, Y1)

Claims (2)

[Scope of utility model registration request] 1. A magnetic body connected to a vibration-isolated object via a shaft, and a plurality of magnetic bodies including the magnetic body, which are laminated so that adjacent poles have the same pole so as to repel each other. The magnetic body is housed in a non-magnetic container with a gap so that the periphery of the magnetic body does not come into contact with the inner wall of the non-magnetic container, and a magnetic fluid is placed in the gap between the container and the magnetic body and between the laminated magnetic bodies. A magnetic fluid damper filled and densely housed, wherein the non-magnetic container is provided with a communication pipe that communicates an upper portion and a lower portion thereof, and a flow rate control valve is provided in the middle of the communication fluid. damper. 2. A magnetic fluid damper according to claim 1, wherein the magnetic body is a permanent magnet.