JPH0650374A - Shock absorber - Google Patents

Abstract

PURPOSE:To secure the high damping force for partitioning a driver from the vibration having the high impact of a shock absorber. CONSTITUTION:Inside the chamber 18 of an outer cylinder 14, magnets 48 and 50 in the upper and lower stages are fixed on the outer cylinder, and a magnet 30 in the intermediate stage is fixed on an inner cylinder 12. These magnets 48, 30 and 50 are arranged, having the repulsive polarity in opposed state. The chambers 16 and 18 of the inner and outer cylinders are charged with each magnetic fluid as working medium.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shock absorber for attenuating shocks, vibrations and the like acting on a seat.

[0002]

2. Description of the Related Art For example, in a seat for an automobile,
A shock absorber that damps vibrations transmitted through a floor surface such as a vehicle floor or vibrations caused by a seated person during traveling is interposed between the seat and the floor surface.

The shock absorber comprises, for example, concentric inner and outer cylinders that are relatively movable, and a working medium composed of a viscous fluid such as working oil (oil) is filled in the chambers of the inner and outer cylinders. Then, the shock absorber is configured so that a buffering force is generated by the flow restriction of the working medium in the chamber via a predetermined orifice, and shock, vibration, etc. can be attenuated.

Normally, the inner cylinder is elastically supported at a neutral position with respect to the outer cylinder under the biasing force of the biasing means, and the speed at which the inner cylinder returns to the neutral position is accompanied by movement in the direction of action of vibration or impact. Vibration can be absorbed by suppressing the.

[0005]

By the way, in the seats of automobiles and the like, in addition to vibrations during normal traveling, pulse-like vibrations with high impact due to steps such as joints of manholes and highways are generated. I often feel.

However, in the known shock absorber, the flow velocity of the working medium is almost the same in both normal vibration and high impact vibration.
The inner cylinder tries to return to the neutral position at a relatively high speed even with high-impact vibration.

Therefore, a sufficient damping force cannot be obtained for high-impact vibration, etc.
It is easily transmitted to the seated person. Such strong shocking vibration may cause a seated person to feel uncomfortable or uncomfortable, reduce the comfort of the seated person, and hinder the performance of safe driving.

It is an object of the present invention to provide a shock absorber having a high damping force capable of isolating a seated person from vibration with high impact.

[0009]

In order to achieve this object, according to the present invention, at least the upper, middle and lower magnetic bodies which are arranged vertically upside down by a predetermined distance are arranged in the outer cylinder. In the chamber, the polarities that repel each other are opposed to each other. Among these magnetic bodies, the upper and lower magnetic bodies are fixed to either one of the inner and outer cylinders, and the middle magnetic body is fixed to the other.

Then, at least a magnetic fluid having a characteristic of increasing its viscosity with an increase in the strength of the magnetic field is filled in the chambers of the inner and outer cylinders as a working medium.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings.

As shown in FIGS. 1 and 2, the shock absorber 10 according to the present invention is provided with concentric inner and outer cylinders 12, 14 which are relatively movable. Then, with the flow of the working medium filled in the chambers 16 and 18 of the inner and outer cylinders,
The shock absorber 10 is configured so that damping force can be generated by relative movement of the inner and outer cylinders 12 and 14 in the expansion and contraction direction.

The inner cylinder 12 has, for example, a screw hole in which a bolt (sheet, etc.) from a seat (not shown) is screwed into the upper end portion.
20 are formed with chambers 16 each filled with a working medium at their lower ends. Where the inner cylinder 12
Is formed integrally with a flange 22 on the outer periphery, and a sleeve 24 made of, for example, a synthetic resin is inserted below the flange, and a nut 28 is attached to a screw portion 26 at the outer periphery of the lower end of the inner cylinder.
The sleeve is attached to the outer circumference of the inner cylinder by screwing.

The sleeve 24 is formed, for example, as an upper half portion 24a and a lower half portion 24b, and a ring-shaped magnetic body 30 is sandwiched between the upper half portion and the lower half portion. Generally, a magnet (permanent magnet) can be used as the magnetic body 30, and the magnet is arranged, for example, such that the upper surface is the S pole and the lower surface is the N pole.

Here, the magnet (magnetic material) 30 of the inner cylinder 12 is sized, for example, to secure a gap 31 through which the working medium can flow between the outer peripheral edge and the inner wall of the chamber 18 of the outer cylinder. Has been formed.

Further, as shown in FIG. 1, a through hole 32 that communicates between the chambers 16 and 18 of the inner and outer cylinders is formed, for example, in the side surface of the inner cylinder 12. As can be seen from FIG. 2 in addition to FIG. 1, the through holes 32 are formed in the vertical position corresponding to the magnet (magnetic material) 30, for example, at 90 ° intervals.

Notches 34 aligned with the through holes are formed at the lower end of the upper sleeve half 24a and the upper end of the lower sleeve half 24b, respectively.

That is, in such a configuration, the magnet
Due to the gap 31 at the outer peripheral edge of 30 and the through hole 32, the chamber 1
The working medium orifices filled in 6, 18 are formed,
These orifices make it possible to limit the flow of the working medium between the chambers.

Although not shown in the embodiment, a detent for preventing the sleeve 24 from rotating with respect to the inner cylinder 12 may be provided between the inner cylinder and the sleeve. With such a configuration, the displacement of the through hole 32 and the notch 34 can be reliably prevented, and the positioning is performed during the assembling work, so that the workability is improved.

As shown in FIGS. 1 and 2, the outer cylinder 14
Are separately formed, for example, into an upper half portion 14a and a lower half portion 14b, and are assembled by sealing between the upper half portion and the lower half portion.

The upper half 14a of the outer cylinder is, for example,
The flange 22 of the inner cylinder and the sleeve 24 are molded so as to have an upwardly facing recess 36 into which the inner cylinder 12 can be freely inserted, and an insertion hole 38 into which the inner cylinder 12 can be freely inserted is formed in the upper wall of the recess. . Further, the lower half portion 14b of the outer cylinder is, for example,
The lower end of the sleeve 24 is formed so that the sleeve 24 can be loosely inserted therein.

Then, the inner cylinder 12 is loosely inserted into the recess 36, the insertion hole 38, and the recess 40 in the lower half of the outer cylinder, so that the inner cylinder becomes the outer cylinder 14. On the other hand, it is incorporated so as to be movable in the axial direction, that is, in the vertical direction in the figure.

As can be seen from FIG. 2, a screw portion 42 is formed on the outer periphery of the lower end of the outer cylinder 14. The screw portion 42 is formed, for example, so that it can be screwed into a screw hole (not shown) to be fixed, such as a vehicle floor of an automobile, and the outer cylinder can be fixed by being screwed into the screw hole.

That is, in the shock absorber 10 having such a structure, the outer cylinder 14 serves as a fixed side, and the vertical movement of the inner cylinder 12 with respect to the outer cylinder enables generation of a damping force.

Here, as shown in FIG. 1, the inner cylinder
The outer cylinder 14 is provided with 12 by means of a biasing means 44, for example.
Maintained in a neutral position against. 2 in addition to FIG.
As can be seen from, as the biasing means 44, for example,
A compression coil spring is available, which is disposed inside the chamber 16 of the inner cylinder and is stretched between the upper end of the chamber and the step 46 on the bottom wall of the recess of the outer cylinder 14. There is.

In such a configuration, the inner cylinder 12 is elastically supported in the neutral position with respect to the outer cylinder 14 under the biasing force of the biasing means (compression coil spring) 44.

The chamber 16 of the inner cylinder and the chamber 18 of the outer cylinder defined between the upper half portion 14a and the lower half portion 14b of the outer cylinder are filled with a working medium made of, for example, a viscous fluid. Has been done. Here, in the present invention, for example, a magnetic fluid having a characteristic of increasing its viscosity with an increase in the strength of a magnetic field is used as a working medium.
The chambers 16 and 18 of the inner and outer cylinders are filled.

Here, a through hole 32 that communicates the chambers 16 and 18 of the inner and outer cylinders is formed in the side surface of the inner cylinder 12, and a gap 31 is formed between the outer peripheral surface of the magnet 30 and the inner surface of the chamber 18. Has been done. In such a configuration,
The through hole 32 and the gap 31 serve as orifices through which the magnetic fluid (working medium) circulates, and the flow of the magnetic fluid between the chambers 16 and 18 through these orifices and between the upper and lower sides of the magnet 30 limits the inner and outer cylinders 12 to each other. The shocks, vibrations, etc. that act on the and 14, are buffered and dampened.

In the present invention, for example,
At the upper and lower ends of the chamber 18 of the outer cylinder, ring-shaped magnets 48, 50 similar to the magnet 30 of the inner cylinder are provided.
, Are arranged and fixed as the upper and lower magnetic bodies.
The magnets 48, 50 of the outer cylinder are arranged such that the polarities thereof repel the polarities of the magnets 30 of the inner cylinder located in the middle stage.

That is, for example, as shown in FIG. 3A, the magnet 30 in the middle stage has an S pole on the upper surface and an N pole on the lower surface.
When the magnets are arranged, the upper magnet 48 is arranged with the lower surface as the S pole, and the lower magnet 50 is arranged with the upper surface as the N pole.

As shown in FIGS. 1 and 3 (A), at the initial position (neutral position) of the inner cylinder 12 with respect to the outer cylinder 14, the upper, middle, and lower magnets 48, 30, 50 are
Due to the biasing force of the biasing means 44 and the viscosity of the magnetic fluid filled in the chambers 16 and 18, they are located in a state in which they are substantially equidistant from each other.

From such a state, for example,
When a downward load acts on the inner cylinder 12 due to the action of high-impact vibration or the like, the inner cylinder resists the biasing force of the biasing means 44, as shown in FIG. Along with it, it drops sharply. Then the chamber
The magnetic fluids 16 and 18 have a clearance 31 that serves as an orifice and a through hole.
Flowing in the direction of the arrow through 32, the inner cylinder 12 is lowered with respect to the outer cylinder 14 while generating a damping force, and the middle magnet 30 and the lower magnet 50 are brought close to each other.

As can be seen from FIG. 3 (B),
Since the middle and lower magnets 30 and 50 are arranged so as to face each other in repulsive polarity, when the inner cylinder 12 descends, the repulsive force between the middle and lower magnets, that is, due to the approaching repulsive polarity, The magnetic field strength increases.

By the way, as shown by the characteristic curve in FIG.
Since the magnetic fluid has a viscous characteristic in which the viscosity rapidly increases as the strength of the magnetic field increases, when the inner cylinder 12 descends with respect to the outer cylinder 14, the viscosity of the magnetic fluid increases and The flow rate of the fluid decreases.

At this time, as shown in FIG. 4, the gap between the middle and lower magnets 30, 50, that is, the flow path of the magnetic fluid is narrowed, so that the flow path resistance is increased and the lower through hole 32 is formed. The flow rate of the magnetic fluid through the is limited.

Then, as shown in FIG. 6, the inner cylinder
The repulsive force (+ F) generated in 12, that is, the force that resists the return of the inner cylinder to the initial position has a non-linear characteristic that rises sharply when the inner cylinder moves beyond a specified range. During a high impact vibration, strong repulsive force acts on the inner cylinder.

In other words, high impact vibration or the like acts,
When the inner cylinder 12 suddenly descends with respect to the outer cylinder 14, the inner cylinder 12 does not rapidly return to the neutral position, but tries to gently return at a speed according to the viscosity and flow amount of the magnetic fluid. . Therefore, vibrations and the like are damped and damped by the shock absorber 10, and the transmission of impact to the seated person is sufficiently suppressed.

As described above, according to the shock absorber 10 of the present invention, the inner cylinder is different from the outer cylinder 14.
The rapid movement of 12 increases the viscosity of the magnetic fluid under the increase of the magnetic field strength and increases the flow resistance of the magnetic fluid. Therefore, the flow velocity of the magnetic fluid is limited, and the rapid return of the inner cylinder toward the neutral position can be sufficiently suppressed, and the gentle return of the inner cylinder damps and buffers high-impact vibrations. It

Therefore, the shock absorber 10 having a high damping force capable of absorbing high-impact vibration or the like is obtained, and the feeling of shock given to the seated person is sufficiently suppressed, so that the comfort of the seated person can be secured.

At least the upper, middle and lower magnets 48, 30, 50 are arranged inside the chamber 18 of the outer cylinder, and the magnetic fluid is used as a working medium in the chamber.
Since it is sufficient to fill 16 and 18, the structure does not become complicated.

Here, although an example of vibration of the inner cylinder 12 in the descending direction is shown, the outer cylinder 14
Even when the inner cylinder moves in the ascending direction with respect to, the middle magnet 30 approaches the upper magnet 48 as the inner cylinder moves upward, increasing the strength of the magnetic field and increasing the viscosity of the magnetic fluid. Therefore, a high damping force is obtained in the shock absorber 10 by the similar operation.

Further, vibrations and the like during normal traveling are not affected by the biasing means.
Since the biasing force of 44 and the damping action due to the combination of the magnetic fluids having the normal viscosity are sufficiently absorbed, the vibration absorbing effect similar to that of the known shock absorber can be sufficiently maintained.

Here, such a shock absorber 10
Are arranged, for example, at locations corresponding to the four corners of the sheet.

By the way, in the embodiment, the magnet 30 in the middle stage is attached to the inner cylinder 12 and the magnets in the upper and lower stages are arranged.
48 and 50 are fixed to the outer cylinder 14, respectively. However, conversely, the middle magnet may be attached to the outer cylinder, and the upper and lower magnets may be attached to the inner cylinder.

Further, the magnets 48, 30, 50 are arranged in the upper, middle,
Although it is embodied as a configuration in which the magnets are arranged in three lower stages, it is sufficient if the magnets adjacent in the vertical direction are arranged so that the repulsive polarities face each other. Therefore, the magnets may be combined in multiple stages.

As described above, if the magnets are further combined in multiple stages, the strength of the magnetic field can be surely increased under the movement of the inner cylinder 12 with respect to the outer cylinder 14. The damping effect of high-impact vibration is further improved.

In the embodiment, the inner cylinder 12
Is mounted on a movable side such as a seat, and the outer cylinder 14 is mounted on a fixed side such as a floor surface.However, on the contrary, the inner cylinder is mounted on the fixed side.
The outer cylinders may be attached to the movable sides, respectively.

Further, the chambers 16 and 18 of the inner and outer cylinders are formed in a shape having a substantially circular cross section, and the magnets 48, 30, 50 are formed in a corresponding ring shape, but the present invention is not limited to this. For example, the chamber and the magnet may be formed in a substantially quadrangular or elliptical cross section.

However, as in the embodiment, the cross sections of the chambers 16 and 18 of the inner and outer cylinders and the magnets 48 and 30,
If the shape of 50 is substantially circular, a smooth flow of the magnetic fluid can be obtained, and therefore, good operation of the shock absorber 10 can be easily obtained without causing a loss in the generation of the damping force.

The shock absorber of the present invention is
Although the present invention is embodied as a configuration to be mounted on an automobile seat, the present invention is not limited to this, and the present invention may be applied to, for example, a shock absorber of a seat of another vehicle such as a train, an airplane, or a ship.

The above-mentioned embodiments are for explaining the present invention and do not limit the present invention in any way.
It goes without saying that the present invention includes all those which are modified or modified within the technical scope of the present invention.

[0052]

As described above, according to the shock absorber according to the present invention, the rapid movement of the other cylinder with respect to the one cylinder limits the flow velocity of the magnetic fluid, and the inner cylinder toward the neutral position. The rapid return of is sufficiently suppressed. Therefore, due to the gradual return of the inner cylinder, a high damping force capable of absorbing high-impact vibration and the like can be secured, the shock feeling given to the seated person is sufficiently suppressed, and the comfort of the seated person is improved. .

At least the upper, middle and lower magnetic bodies are arranged in the chamber of the outer cylinder, and
Since it is sufficient to fill the chamber with the magnetic fluid as the working medium, the structure does not become complicated.

Further, if the cross section of the chamber of the inner and outer cylinders and the magnetic body are made substantially circular, a smooth flow of the working medium can be obtained, so that there is no loss in the generation of damping force, and a good shock absorber is obtained. Operation is easily obtained.

Further, if the magnetic fluid is circulated through the outer peripheral edge of the middle magnetic body, the gap between the inner surfaces of the chambers, and the through holes formed in the inner cylinder at the upper and lower positions sandwiching the middle magnetic body,
The flow path resistance of the magnetic fluid changes as the inner cylinder moves. That is, in addition to the increase in the viscosity of the magnetic fluid, the flow of the magnetic fluid is further restricted, so that a high damping force can be obtained more reliably.

Further, if the magnetic body is further multi-staged, the magnetic field strength increases at a plurality of locations in the chamber, so the viscosity of the magnetic fluid surely rises, and also from this point, a high damping force can be obtained. .

[Brief description of drawings]

FIG. 1 is a schematic longitudinal sectional view of a shock absorber according to the present invention in a neutral position of an inner cylinder.

FIG. 2 is an exploded perspective view of the shock absorber with a part thereof broken away.

FIG. 3 is a neutral position and a lowered position of the inner cylinder;
It is a characteristic curve of each magnetic field.

FIG. 4 is a schematic vertical sectional view of the shock absorber in the lowered position of the inner cylinder.

FIG. 5 is a viscosity characteristic curve of a magnetic fluid.

FIG. 6 is an operating force characteristic curve of the inner cylinder.

[Explanation of symbols]

 10 Shock absorber 12 Inner cylinder 14 Outer cylinder 16, 18 Chamber 30 Magnetic material (middle magnet) 31 Gap (orifice) 32 Through hole (orifice) 44 Biasing means 48 Magnetic material (upper magnet) 50 Magnetic material (lower step) Magnet)

Claims (4)

[Claims] 1. Concentric inner and outer cylinders, each having a chamber filled with a working medium, movably mounted therein: one cylinder under a biasing force in a neutral position with respect to the other cylinder. A biasing means elastically supported on;
In a shock absorber that produces a damping force due to the flow of the working medium in the chamber of the inner and outer cylinders according to the change in the relative position of the inner and outer cylinders, in the chamber of the outer cylinder, it is vertically separated by a predetermined distance. At least the upper, middle, and lower magnetic bodies that are arranged are arranged with their repulsive polarities facing each other, and
The lower magnetic body is fixed to one of the inner and outer cylinders, and the middle magnetic body is fixed to the other, and at least the magnetic fluid that has the property of increasing its viscosity as the magnetic field strength increases increases the working medium. A shock absorber characterized by being filled in the chambers of the inner and outer cylinders. 2. The inner and outer cylinders are formed into a cylindrical shape, each chamber of the inner and outer cylinders is formed into a substantially circular cross section, and the magnetic body is formed from a donut-shaped magnet corresponding to the cross sectional shape of the chamber. The shock absorber described in 1. 3. The upper and lower magnetic bodies are fixed to the outer cylinder, and the middle magnetic body is fixed to the inner cylinder, and between the outer peripheral edge of the middle magnetic body and the chamber inner surface of the outer cylinder,
A through hole that forms a gap through which the magnetic fluid can flow and that allows the magnetic fluid to flow by communicating between the chambers of the inner and outer cylinders is provided at each of a plurality of positions separated from each other above and below the middle magnetic body. The shock absorber according to item 1 or 2. 4. The shock absorber according to any one of claims 1 to 3, wherein the magnetic bodies are arranged in multiple stages with the repulsive polarities facing each other.