JPS61211545A - Magnetic fluid damper - Google Patents

Abstract

PURPOSE:To damp the vibration effectively by arranging a plurality of electromagnets along the axial direction of cylinder while differentiating the fields of said magnets in the axial direction of cylinder. CONSTITUTION:Magnetic fluid 25 is contained in the cylinder 22 of magnetic fluid damper 1 while a plurality of electromagnets 26a-26e are arranged around the cylinder 22. Then voltage is applied across the electromagnets to increase the viscosity at the portions 25a-25e of the magnetic fluid 25 axially outward from the central portion 25c thus to increase the damping amount. Consequently, nonlinear damping characteristic can be achieved resulting in desired damping.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a damper for reducing vibration, and more particularly to a magnetic fluid damper suitable as a vibration isolator for an air cleaner for an internal combustion engine.

Prior Art Conventional vibration isolation mechanisms for air cleaners for internal combustion engines use the following methods to damp vibrations from the carburetor:
For example, as shown in Japanese Unexamined Patent Publication No. 57-33260, an elastic member such as rubber is used. Furthermore, oil dampers and the like that use cylinders containing oil for absorbing vibrations and shocks are also known.

Problems to be Solved by the Invention As mentioned above, a damper using an elastic member such as rubber can perform a good vibration damping effect in a specific frequency range, but it cannot cover the entire frequency range in which it is used. I can't. If an elastic member such as rubber is used, in conventional technology, if the engine type or vehicle is different, an elastic member of a different shape or material is used depending on the engine or vehicle. There are flaws that you have to get used to.

Further, in the case of an oil damper, as in the case of an elastic member such as rubber, there is a drawback that the size and shape must be changed depending on the engine or vehicle to be used.

Therefore, an object of the present invention is to provide a damper that can effectively damp vibrations over the entire normal rotation range, that is, the normal frequency range, regardless of the type of engine or vehicle used.

Means for Solving the Problems A magnetic fluid damper according to the present invention replaces the oil in a conventional oil damper with a magnetic fluid, houses this in a cylinder, and installs a plurality of electromagnets along the axial direction of the cylinder. The magnetic field of this electromagnet is varied in the axial direction of the cylinder.

By detecting changes in factors that cause fluctuations in the working vibration frequency, such as engine rotational speed, and applying different voltages to the electromagnet in the axial direction based on this, it is possible to generate different strengths in the axial direction. By generating a magnetic field in a magnetic fluid and changing the viscosity of the magnetic fluid in the axial direction, effective damping can be achieved over almost the entire range of common frequencies.

Embodiment A magnetic fluid damper 1 according to the present invention connects an air cleaner 2 and a carburetor 3 as shown in FIG. The carburetor 3 is mounted on an engine 5 via an intake manifold 4, and the air cleaner 2 is mounted on the carburetor 3 via a mounting portion 6.

The vibration system of the apparatus shown in FIG. 2 is shown in FIG. 3. In addition, in this Figure 3, the same symbols as in Figure 2 are the same.
or equivalent parts.

As shown in FIG. 1, the magnetic fluid damper 1 has a cylinder 22 with a connecting part 21 formed at one end and a connecting part 23 at the other end, and is inserted into the cylinder 22, similar to the conventional oil damper. It has a piston 24. Naturally, the cylinder 22 is made of a material that allows the magnetic field to pass through. The cylinder 22 contains not ordinary oil but a magnetic fluid 25, and around the cylinder 22 there are a plurality of electromagnets 26a, 26b, 26c.
.

26d and 26e surround the cylinder 22 and are arranged in several sets in the axial direction of the cylinder 22. These electromagnets 2
Different voltages are applied to 6a to 26e depending on the rotational speed of the engine 5. For example, the voltage of the electromagnet 260 is minimized, and the electromagnet 260 is moved in the axial direction from this point.
b, 26d and electromagnets 268, 26e, each electromagnet 26a, 28b, 26c
, 26d.

A portion 25a of the magnetic fluid 25 corresponding to 26e.

The viscosity of 25b, 25c, 25d, and 25e also increases from the central portion 25c toward the outside in the axial direction, and the amount of attenuation increases accordingly.

In this way, according to the present invention, a nonlinear damper can be obtained. Therefore, in the magnetic fluid damper according to the present invention, it is possible to freely select a magnetic field gradient suitable for each imaging system, and the damper main body can be made common.

Next, another embodiment of the present invention will be described with reference to FIG.

The magnetic fluid damper 31 according to the present invention has an inner cylinder 33 in which a connecting part 32 is formed at one end, and an outer cylinder 34 surrounding the inner cylinder 33. A piston 36 having a piston rod 35 is inserted into the inner cylinder 33. There is. An orifice 37 is formed in the piston 36, and the piston rod 35 extends through the end of the outer cylinder 34, at which end another connection 38 is formed. and,
A magnetic fluid 39 is contained within the inner cylinder 33,
An electromagnet 40 is arranged around this inner cylinder 34.

The magnetic fluid damper 31 configured in this manner is connected to the carburetor 3 via its connecting portions 32, 38 as shown in FIG.
and air cleaner 2.

The electromagnets 40 are arranged as shown in FIG. 5, for example. That is, a plurality of (six in the case of the fifth cause) electromagnets 40
are arranged in the circumferential direction on the outside of the inner cylinder 33 shown by the dashed line to form one set, which in turn is arranged in several sets (
In FIG. 5, three sets are provided, and a magnetic field is generated by applying a voltage.

Next, the operation of the magnetic fluid damper according to the present invention will be explained with reference to FIGS. 7 and 8.

As described above, the electromagnets 40 are arranged circumferentially and axially around the cylinder 33 that houses the magnetic fluid 39, so that each electromagnet 40a, 40 is disposed as shown in FIG.
Vo, Vz, V on b, 40c, 40d, 40e
2, and the increasing voltages are respectively v2) Vl, Vo, Vl, V
2, each portion 39 of the ferrofluid within the cylinder 33
a, 39b.

A magnetic field is formed in 39c, 39d, and 39e that increases from the center toward the outside in the axial direction, and accordingly, each portion 3
The viscosities of 9a to 39e also increase toward the outside in the axial direction.

As a result, a nonlinear shock absorber, ie, a damper, whose damping characteristics differ depending on the magnitude of the amplitude can be obtained.

In the embodiment shown in FIG. 7, when the operating speed is low but the amplitude is large, for example, the orifice portion of the piston 36 is a portion 39d of the magnetic fluid 39.

39e, greater damping can be achieved than when the viscosity of the magnetic fluid 39 is uniform throughout the fluid.

In the embodiment shown in FIG. 8, the voltage of the central electromagnet 40C is the highest (V3), and the voltage of the central electromagnet 40C is V4. It gradually becomes smaller with V5. Therefore, the viscosity of each part 39a to 39e of the magnetic fluid 39 is also the same as that of the central part 3.
9c is the largest, portions 39b, 39d and portion 3
9a.

It becomes smaller sequentially to 39e.

In this embodiment, for example, when the frequency is high and the amplitude is also high, the piston 36 passes through a region with low viscosity, and conversely, when the frequency is low and the amplitude is also low, it is damped in a region with high viscosity. This results in a high damping effect. Therefore, the embodiment shown in FIG. 8 has desirable characteristics as a shock absorber for an automobile, and can obtain the damping characteristics shown by reference numeral 71 in FIG. 9.

Furthermore, by changing the viscosity on the extension side and the contraction side of the shock absorber, it is possible to obtain a shock absorber with different damping characteristics depending on the extension and contraction.

Incidentally, the curves indicated by reference numerals 72 and 73 in FIG. 9 are curves showing unfavorable damping characteristics of the damper according to the prior art.

Effects As described above, the magnetic fluid damper according to the present invention has non-linear damping characteristics, and can perform desired damping depending on the engine rotation speed or the operating speed of the operating part, and at the same time can perform different types of operation. It can also be applied to a wide range of areas.

Although this control has been described as being carried out by controlling the voltage of the electromagnet, it can also be carried out by changing the winding of the electromagnet.

Although the present invention has been explained above mainly as a damper for an air cleaner of an internal combustion engine, it is easy to understand that it is applicable as a damper for various vibration damping or vibration isolation purposes without being particularly limited to these. Will.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view schematically showing a magnetic fluid damper according to the present invention, FIG. 2 is a schematic side view showing how the magnetic fluid damper according to the present invention is installed, and FIG. 3 is a schematic side view of the device shown in FIG. 4 is a cross-sectional view showing another embodiment of the present invention, FIG. 5 is an enlarged perspective view showing the arrangement of the electromagnets shown in FIG. 4, and FIG. 6 is the same as FIG. 4. FIGS. 7 and 8 are views showing other embodiments of the present invention, and FIG. 9 is a view showing the damping characteristics of the shock absorber. . 1... Magnetic fluid damper, 22... Cylinder, 24... Piston, 25... Magnetic fluid, 26... Electromagnet.

Claims (3)

[Claims] (1) It has a cylinder containing a magnetic fluid and a plurality of electromagnets arranged along the axial direction of the cylinder so as to magnetize the magnetic fluid, and the strength of the magnetic field of the electromagnet is controlled by the magnetic field of the cylinder. A magnetic fluid damper characterized in that the viscosity of the magnetic fluid is varied in the axial direction by varying the viscosity of the magnetic fluid in the axial direction. (2) The magnetic fluid damper according to claim 1, wherein the strength of the magnetic field of the electromagnet increases from the center toward the outside in the axial direction of the cylinder. (3) The magnetic fluid damper according to claim 1, wherein the strength of the magnetic field of the electromagnet decreases from the center toward the outer side in the axial direction of the cylinder.