JPH039536Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic fluid damper that combines a magnetic fluid and a magnet.

Conventionally, in precision equipment or measuring instruments/buildings,
A method of absorbing and damping vibration by incorporating it into the lower end of the device is generally adopted. Such a vibration isolator or the like is generally composed of a vibration isolator made of rubber filled with air.

However, although such a rubber vibration isolator can greatly attenuate vibrations of several tens of hertz or more, it cannot absorb or attenuate most of the vibrations generated below several tens of hertz, for example, 3 hertz or less.

For this reason, it has conventionally been proposed to absorb and damp mechanical vibrations by combining a magnetic fluid damper 2 in parallel with a rubber vibration isolator 1, as shown in FIG.

As shown in FIG. 2, the damper 2 using this magnetic fluid is constructed by alternately stacking magnetic bodies 6 with the same polarity adjacent to each other using permanent magnets 5 in a cylindrical container 4 made of a non-magnetic substance. It is configured. 7 indicates a magnetic fluid in which magnetic particles such as magnetite or ferrite are uniformly dispersed in various solvents such as water, kerosene, and various hydrocarbons, and is sealed in the 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 in order to obtain desired characteristics. The damping constant is adjusted by the magnetic field of the permanent magnet 5 while controlling the viscosity of the magnetic fluid 7, thereby absorbing and attenuating low-frequency mechanical vibrations applied to a shaft 8 continuously formed on the object to be vibration-isolated. .

However, these magnetic fluid dampers have the disadvantage that during use, the magnetic fluid evaporates from the opening 4 of the container 4, and as the viscosity increases, the damping constant changes, making it impossible to obtain a sufficient damping effect. There is.

In view of this, the present invention has been developed by placing a magnetic fluid together with a magnetic fluid in a non-magnetic container, a magnetic fluid solvent, a non-magnetic liquid having low compatibility with the magnetic fluid solvent, and a non-magnetic powder, so that the latter is caused to flow above the former due to a magnetic field gradient. The main purpose of the present invention is to propose a magnetic fluid damper of this type that suppresses evaporation of the magnetic fluid by floating and has a stable damper effect over a long period of time.

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 example of the present invention,
The same parts as those shown in the example of FIG. 2 will be described with the same reference numerals. No. 9 indicates an oil having an extremely small amount of evaporation and low compatibility with the magnetic fluid.
For oil 9, if a magnetic fluid with water as the solvent is used, use mineral oil, polyolefin-based synthetic oil, paraffin-based synthetic oil, ester, ether, non-volatile oil such as alkylnaphthalene, fluorocarbon, silicone oil, etc. I can do it. Further, when a magnetic fluid using oil, ester, ether, alkylnaphthalene, etc. as a solvent is used, fluorocarbons and silicone oils can be used. Since this oil 9 is a non-magnetic material, if its specific gravity is smaller than that of the magnetic fluid 7, it naturally moves to the lower magnetic field side, and even if it has a larger specific gravity, it floats to the lower magnetic field side due to the magnetic field gradient of the magnetic fluid damper. , the entire air-liquid interface of the magnetic fluid 7 is covered, and even if the oil 9 evaporates, the magnetic fluid will not dissipate unless it completely disappears, and thus evaporation of the magnetic fluid can be suppressed.

Incidentally, the same effect can be obtained even if the oil 9 is replaced with a non-magnetic powder such as aluminum powder. In that case, the magnetic fluid will not dissipate in any environment in which the damper is used, so evaporation of the magnetic fluid will be suppressed.

When oil and non-magnetic fluid are mixed into magnetic fluid, a non-magnetic powder layer is formed on the upper layer of the magnetic fluid, and a layer of oil is further formed on top of that, so the evaporation of the magnetic fluid is completely prevented. This will be prevented.

As explained above, according to the present invention, in a magnetic fluid damper in which a laminated magnet connected to an object to be vibration-isolated is housed in a non-magnetic container, and a magnetic fluid is sealed in the gap between the container and the magnet, A solvent for the magnetic fluid, a non-magnetic liquid and a non-magnetic powder having little compatibility with the solvent for the magnetic fluid are placed in the container together with the magnetic fluid, and evaporation of the magnetic fluid solvent is suppressed by the non-magnetic liquid and the non-magnetic powder having little compatibility. Therefore, even if the non-magnetic oil injected for sealing evaporates when the damper is installed in a high-temperature, harsh environment, a layer of non-magnetic powder still remains on top of the magnetic fluid layer. Evaporation of the magnetic fluid is suppressed as long as the magnetic powder layer does not disappear, and as a result, the initially set damper characteristics can be maintained for a long period of time.

[Brief explanation of the drawing]

Figure 1 is a diagram showing an example of a conventional device of this kind;
The same figure is a sectional view showing the detailed structure, and FIG. 3 is a sectional view showing an example of the device of the present invention. 4...Nonmagnetic container, 5...Permanent magnet, 6...
Magnetic material, 7...Magnetic fluid, 9...Oil.

Claims (1)

[Claims for Utility Model Registration] A magnetic fluid damper in which a laminated magnet connected to an object to be vibration-isolated is housed in a non-magnetic container, and a magnetic fluid is filled in a gap between the container and the magnet, the container having: A solvent for the magnetic fluid, a non-magnetic liquid and a non-magnetic powder with little compatibility with the solvent of the magnetic fluid are added together with the magnetic fluid, and the evaporation of the magnetic fluid solvent is suppressed by the non-magnetic liquid and the non-magnetic powder with little compatibility. A magnetic fluid damper characterized by: