Tank piston with improved seal and wiper

Details Tank piston with improved seal and wiper Tank piston with improved seal and wiper

1999-12-30

2001-12-04

Knight, Anthony (Department: 3626)

Seal for a joint or juncture

Seal between relatively movable parts

Piston ring or piston ring expander or seat therefor

C277S441000, C277S442000, C220S226000

Reexamination Certificate

active

06325384

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates generally to systems for the transportation and/or storing of viscous materials such as grease, oil, ink, and the like, and semisolid materials such as comminuted food products, and the like, in bulk quantity and, more particularly, to a tank and piston structure therefor.
BACKGROUND OF THE INVENTION
Tanks for the bulk transport and/or storage of semisolid and liquid materials of the kind comprising a tank with a movable piston therein are well known in the art. Examples of such tanks may be found in U.S. Pat. Nos. 3,828,988; 4,721,235; 5,114,054; and 5,341,726. The tanks usually have follower pistons with pneumatically expandable seals surrounding one end of the tank for seating the piston relative to the tank to accommodate changes in the interior cross-section of the tank. The seal is generally positioned between circumferential flanges affixed to the outer surface of the tank in order to axially retain the seal during movement of the piston. The tanks also generally have pads positioned about the piston and extending radially outwardly therefrom for preventing canting of the piston as the piston moves within the tank.
As indicated above, the prior art seals are usually hollow and capable of being filled with air to cause the seals to expand. The hollow portion or chamber of the seal may be filled and depleted of air through a valve structure in communication with the chamber and disposed within the piston. The valve is accessible through a rear opening in the piston. Since the seal is naturally between the outer surface of the piston and the inner surface of the tank, and is in contact with the inner surface of the tank as the piston reciprocates within the tank, the seal is subject to abrasion and wear. Also, because the seal is pneumatic, there is always the possibility that a puncture will develop and render the seal useless. Thus, although pneumatic seals are efficient, they are prone to failure. Furthermore, the friction created on the seal by the reciprocating piston may occasionally cause the seal to roll out of position. Additionally, pneumatic seals are difficult to fasten securely to the piston because they cannot be punctured by a fastener.
It has been suggested that the design of the seal be such as to effect a wiping action against the inner surface of the tank. This however, is subjecting the seal to more wear and exposing the seal to a greater possibility of failure.
In view of the above, it is an object of the present invention to provide an improved seal structure for a tank piston.
It is another object of the present invention to provide a piston seal that will accommodate expansion while providing a longer wear life.
It is yet another object of the present invention to provide a tank piston structure that includes an improved wiper structure.
It is still another object of the present invention to provide a tank piston that has an improved wiper structure for the inner surface of the tank, and having an improved seal structure that moves along the inner surface of the tank with less friction.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, an elastic, deformable seal structure for a tank piston includes an interior, annular chamber that is filled with an open celled foam material. The seal is preferably defined by an annular base coupled to a crown portion, which together define the interior, annular chamber. The open celled material may be rubber, polyurethane, or like resilient material that is compressible and is elastic to expand back substantially to its original volume.
The seal is substantially annular and disposed on the outer surface of the piston and surrounding the same, preferably near one end, and is axially retained by a circumferential groove or channel disposed in the outer surface of the piston.
In one embodiment of the seal, the crown portion is defined by a dome-shaped member. In another embodiment, the crown portion is defined by two axially spaced, parallel walls, each coupled to an angled top wall. The top walls join to form an apex.
According to another aspect of the present invention, the seal is surrounded by a friction reducing layer, possibly of Teflon®, which may be shrink-wrapped around the seal. The friction reducing layer specifically reduces the kinetic coefficient of friction between the seal and the inner surface of the tank.
According to yet another aspect of the present invention, a circumferential wiper structure extends from the outer surface of the piston near the discharging end of thereof, and is in abutting relationship with the inner surface of the tank. The end of the wiper abutting the inner surface of the tank preferably includes a bevel. Optionally, a second wiper may be disposed at the opposite end of the tank.
In one form, the wiper is an elongated circumferential ring that extends at a 45&thgr; angle, relative to an axis of the piston, towards the inner surface of the tank. The ring may be formed of a suitable plastic.
In the preferred embodiment of the seal, a support strip is placed between the open cell foam material and the base portion. The support strip is preferably made of the same material as the seal itself.


REFERENCES:
patent: 2144082 (1939-01-01), Randall
patent: 2859061 (1958-11-01), Reid
patent: 3043468 (1962-07-01), Horner
patent: 3055533 (1962-09-01), Reese et al.
patent: 3125346 (1964-03-01), Poltorak
patent: 3307733 (1967-03-01), DeBock
patent: 3828988 (1974-08-01), Berry
patent: 3926332 (1975-12-01), Okamoto
patent: 4004708 (1977-01-01), Boyd
patent: 4130217 (1978-12-01), Hills et al.
patent: 4147274 (1979-04-01), Hall et al.
patent: 4178000 (1979-12-01), Kuttner
patent: 4355736 (1982-10-01), Schumacker et al.
patent: 4371090 (1983-02-01), Ogarek et al.
patent: 4449713 (1984-05-01), Ishido et al.
patent: 4532800 (1985-08-01), Coleman
patent: 4721235 (1988-01-01), Watson
patent: 4842160 (1989-06-01), Piso
patent: 5114054 (1992-05-01), Watson
patent: 5137283 (1992-08-01), Giarrusso et al.
patent: 5290045 (1994-03-01), Terauchi et al.
patent: 5341726 (1994-08-01), Watson
patent: 5385081 (1995-01-01), Sneddon
patent: 3725360-A1 (1989-02-01), None

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