Brakes – Internal-resistance motion retarder – Using a rotary-type fluid damper
Patent
1989-02-10
1990-07-03
Halvosa, George E. A.
Brakes
Internal-resistance motion retarder
Using a rotary-type fluid damper
16 51, 192 58B, 192 58C, F16D 5702
Patent
active
049383221
DESCRIPTION:
BRIEF SUMMARY
FIELD OF TECHNOLOGY
This invention relates to a damper using a high-molecular viscous fluid material such as polyisobutylene with a view to utilize its high viscous drag against shearing force for buffering or damping the external force, thereby providing a variety of potential applications.
TECHNICAL BACKGROUND
It is well known that a conventional damper utilizes the turbulence of the oil it contains to absorb the shock imparted by an external force. Such turbulence occurs when the oil passes through narrow slits provided within the damper as oil is pressed by the external force.
However, with such a damper, high precision is required for the make of the slits to accurately generate a required resisting force in order to accurately produce the required damping effect. Morever, as oil cannot be compressed when a strong external force is abruptly applied to it, the external force is apt to be directly received by the strucural members the damper is supposed to protect. To overcome this problem, a damper is normally designed to have an excessively high strength against external force, making in turn its overall size very bulky. Besides, the slits are liable to become narrow as dust and other foreign matters are caught by the slits and eventually clogged to completely block the flow of oil.
In order to eliminate these disadvantages of the damper of the conventional designa as described above, an improved damper has been proposed, which basically comprises two independent solid members arranged in such a manner that they are movable relative to each other and have surfaces located vis-a-vis and close to each other and a highly viscous liquid material filled therebetween so that it can provide resistance against external force due to the viscous drag of the liquid material against shearing force that can be generated without raising the internal pressure of the liquid when an external force is applied thereto.
A typical damper which was realized in relatively early days on the basis of this design a concept comprises a casing in which a certain number of movable discs are radially and perpendicularly fitted to a rotary shaft and a same number of fixed discs are fitted to the casing in such a manner that the movable discs and the fixed discs are arranged alternatively with an appropriate clearance between any two adjacent discs and the oil which is contained within the casing fills the spaces between the discs.
With a damper having a configuration as described above, when an external force is applied to the rotary shaft, the movable discs fitted thereto and the fixed discs fitted to the casing are caused to move relative to each other and the viscous liquid filling the spaces between the discs generates viscous drag against the shearing action of the external force to bring forth the overall effect of the damper. However, with such an arrangement, the distance between the two adjacent discs has to be precisely identical for all the discs. If not, the portion of the viscous fluid found between a pair of discs having a relatively small clearance generates a larger viscous drag than the portion of the fluid found between a pair having a relatively large clearance, causing an unreasonably large stress to occur in the are having a large viscous drag that can eventually damage the damper, since the discs are rigidly fitted either to the casing or the rotry shaft and the clearance between a pair of adjacent discs and are not adjustable.
Consequently, manufacture of such a damper requires a considerable high precision. Moreove, such a damper is not capable of altering its damping effect by altering the surface area of the discs because they are rigidly fitted to the supporting members and not accessible from outside, while the amount of viscous drag is proportional to the surface area of the adjacent discs which are facing to each other. This means that if a damper having a different damping effect is needed, a completely new damper has to be provided.
In order to eliminate the drawbacks of the above described dampe
REFERENCES:
patent: 923565 (1909-06-01), Newcomb
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patent: 2959252 (1960-11-01), Jamiesas
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patent: 3651903 (1972-03-01), Butler et al.
patent: 4683997 (1987-08-01), Stockmar et al.
Hayakawa Tatsuya
Nakayama Youjirou
Ohshima Kazuyoshi
Sugasawara Seiji
Tamura Seiichiroh
Halvosa George E. A.
Sugatsune Industrial Co. Ltd.
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