Spring devices – Fluid – Expansible-contractible chamber device
Reexamination Certificate
1999-11-08
2001-01-23
Schwartz, Chris (Department: 3613)
Spring devices
Fluid
Expansible-contractible chamber device
C188S322220, C267S064110
Reexamination Certificate
active
06176475
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention pertains to air dampers with adjustable air flow rates. The adjustable air flow rates are achieved by the degree of graining or texturing of a plate which contacts the seal or by inserting a mold or assembling a media, such as a filter into a shaft or housing of the damper.
2. Description of the Prior Art
In the prior art, air dampers are known. However, typical prior art air dampers do not allow for simple adjustment of the air flow rate which controls the damping. As the damping is typically controlled by an orifice through which the air flows, such adjustment is typically done by varying the size of the orifice which requires a re-design of the air damper.
The damping rate of prior art dampers can be limited due to tooling restrictions, and tooling variations can create damping variations. Similarly, slow damping rates are difficult to achieve with prior art designs. Likewise, small variations in damping rates are difficult to achieve with prior art designs.
Examples of prior art include U.S. Pat. No. 5,603,574 entitled “Fluid Dampened Support Having Variable Stiffness and Damping”, issued on Feb. 18, 1997 to Ide et al. which discloses a fluid dampened support having variable stiffness and damping. Electric discharge machining is used for the purpose of achieving fine tolerances. U.S. Pat. No. 5,697,477 entitled “Air Damper”, issued on Dec. 16, 1997 to Hiramoto et al. discloses an air damper with a tapered functional damper with a plunger and a piston, and further discloses a cylindrical tapered body and an O-ring resulting in two separate chambers. U.S. Pat. No. 5,647,578 entitled “Latch Mechanism”, issued on Jul. 15, 1997 to Bivens discloses a latch mechanism with an O-ring with a tapered surface. U.S. Pat. No. 4,877,155 entitled “Spill Protecting Apparatus”, issued on Oct. 31, 1989 to Tull discloses an apparatus which includes an air damper which includes a seal at an open end of the cylinder and compressed gas in two chambers so that both air and friction retard or damp movement of the piston.
OBJECTS AND SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an air damper in which the damping rate can be varied without the need for a substantial re-design of the air damper.
It is therefore a further object of this invention to provide an air damper in which slow damping rates can be achieved.
It is therefore a still further object of this invention to provide an air damper in which damping rates are repeatable from damper to damper.
It is therefore a still further object of this invention to provide an air damper in which small changes in damping rates can be achieved.
It is therefore a still further object of the present invention to provide an air damper in which the damping rate can be varied with a minimal additional cost.
These and other objects are attained by providing an air damper in which the damping is effected by air passing between a seal and a textured or grained plate within the plunger. By varying the depth and/or degree of texturing or graining, the effective air flow area can be varied thereby varying the degree of damping. Alternatively, a mold can be inserted or a media, such as a filter, can be assembled into a shaft or housing of a damper in order to vary the amount of air flow.
More particularly, the air damper includes a shaft, a seal, a housing, a retainer and a plunger, the plunger having the textured surface. In operation, when the damper is extended, the seal extends between the outer diameter of the seal and the inner diameter of the housing and between the top grained surface of the plunger and the bottom wall of the seal. The grained surface on the plunger allows a very accurately controlled amount of air to be metered from one side of the seal to the other, thereby causing a slow consist damped rate. This airflow rate can be varied by simply changing the grained finish. These variations in airflow rate can be small or large and are very repeatable from one damper to another.
REFERENCES:
patent: 4877155 (1989-10-01), Tull
patent: 5085397 (1992-02-01), Henkel
patent: 5183137 (1993-02-01), Siwek et al.
patent: 5257680 (1993-11-01), Corcoran et al.
patent: 5295564 (1994-03-01), Stadelmann
patent: 5603574 (1997-02-01), Ide et al.
patent: 5647578 (1997-07-01), Bivens
patent: 5697477 (1997-12-01), Hiramoto et al.
patent: 5713623 (1998-02-01), Mattingly
Bella Joseph J.
Bivens Steven L.
Chisholm Lisa E.
Little Gary R.
Illinois Tool Works Inc.
Pitney, Hardin, Kipp and Szuch LLP
Schwartz Chris
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