GREASE TANK WITH ANTI-TIPPING FOLLOWER

Abstract

A tank for transporting, storing, and dispensing viscous materials is disclosed having a cylindrical body, and spherical ends. The tank further comprises an ellipsoidal follower device used to force the viscous material through the tank, the follower device having an upper half, and lower half, and a centerline. A plurality of stabilizing fins are rigidly connected to the ellipsoidal follower device at the centerline and extending axially along the tank's inner wall, the stabilizing fins disposed between a periphery of the ellipsoidal follower device and an inner wall of the cylindrical body. The fins serve as an anti-tipping device to maintain the follower in the proper orientation even upon rested in a horizontal position.

Description

BACKGROUND

This invention relates generally to a system for transporting or storing viscous materials, such as greases, oils, and non-Newtonian fluids, as well as liquid materials, such as inks, etc., in bulk quantities, and more particularly to a tank adapted to quickly and efficiently unload or dispense the material contained therein.

Vast amounts of viscous materials are used in transportation and industry. Thick, lubricating greases are used to lubricate vehicles and machinery, and thick, viscous chemicals are used in industry. In the food processing arts, cheeses, cream, food pastes and the like must be moved from point to point without excessively degrading the food's quality and freshness. In the manufacture of fine chemicals and pharmaceutical products, viscous materials are often used, and maintaining the quality of these viscous materials is of vital importance.

Delivering and dispensing viscous materials has always presented a challenge to manufacturers because these materials tend to adhere to their containers and through repeated refills eventually coat the pumping machinery used to deliver the viscous materials. Prior art methods of delivery viscous fluids have concentrated on establishing and maintaining a fluid tight seal between pushing pistons or follower plates, and sidewalls of the containers of viscous materials. The devices of U.S. Pat. No. 5,248,069 to Consaga et al.; U.S. Pat. No. 5,297,702 to Crosby, et al.; and U.S. Pat. No. 5,312,028 to Hume are all directed to establishing a close seal.

These prior art devices, however, are highly susceptible to disruption if the sidewalls of the viscous material container becomes even slightly out of round or are dented. Moreover, the systems of Consaga et al. and Hume in particular, require high precision in all its parts, and require relatively bulky and expensive equipment.

To overcome this obstacles, reusable tanks were developed for dispensing thick viscous materials, from a sealed pressure container having sidewalls of generally cylindrical shape, having an inert gas inlet at a top region, and a viscous material ingress and egress opening at a bottom region, wherein a pressurizing follower device is located inside the sealed pressure container, said pressurizing follower device having a lower body portion and an upper body portion. The lower body portion and upper body portion are preferably connected in a circular interface region which is smaller in diameter than the internal cross-sectional diameter of the cylindrical sealed pressure container and said pressurizing follower device having means to prevent the circular interface region from directly contacting the inside of the sidewall of the cylindrical container. Such a tank is disclosed in U.S. Pat. No. 5,435,468 to Clark II, the contents of which are fully incorporated herein by reference.

In use of the system the container, when filled with viscous material through its ingress and egress opening, raises the pressurizing follower device in the sealed pressure container and forms a viscous material seal between the interface region of the pressurizing follower device and the inside of the sidewall of the container. By applying inert gas pressure to the pressurizing follower device from above, the pressurizing follower device will force the viscous material out of the container through the viscous material ingress and egress opening. The apparatus of the invention can be repeatedly refilled and reused without any intermediate cleaning or reconditioning of the container.

The pressurizing follower device is contained inside the sealed pressure cylinder and the pressurizing follower device has a lower body portion which is generally rounded in shape to conform to the shape of the generally hemispherical lower end of the pressure cylinder and an upper body portion which is generally rounded in shape to conform to the shape of the generally hemispherical upper end of the pressure cylinder. The upper body portion of the follower device has a small orifice formed in a top portion thereof and said upper body portion and lower body portion are preferably connected together along a circular interface region which is smaller in diameter than the internal cross-sectional diameter of the cylindrical pressure container. The follower device is weighted in its lower body portion so that the weight of the viscous material displaced by its lower body portion is about equal to the total weight of the follower device. In this way, the pressurizing follower device resides in the viscous material with the viscous material coming up to about its interface region. The follower device preferably has a plurality of fins extending radially outwardly from the vicinity of the interface region. These fins have narrow terminating points or edges which generally do not make contact with the inside surface of the sidewalls of the cylinder, and if they do, only make a slight scrape line of the viscous material on the insides of the sidewalls of the cylinder, which scrape lines are readily filled in.

In the use of the system, the pressure cylinder is filled with viscous material through a common ingress and egress opening near the bottom of the tank, which raises the pressurizing follower device in the pressure cylinder and forms a viscous material seal between the interface region (and the fins) and the inside of the sidewalls of cylinders. By applying inert gas pressure to the pressurizing follower device from above, the pressurizing follower device will force the viscous material out of the container through the viscous material ingress and egress opening, all the while maintaining the seal between the pressuring follower device and the inside of the sealed pressure cylinder.

The problem with the prior art system is demonstrated in FIGS. 1 and 2. When the tanks are being transported, it has been discovered that the tanks are sometimes laid horizontal for brief periods against expressed instructions forbidding this practice during unloading, exchanging vehicles, storage, and the like. Since the follower device has a radial dimension that is smaller than the inner diameter of the tank, when the tank is laid on its side the follower device can tip or tilt when compared with the longitudinal axis of the tank. When tank is returned to the horizontal position, the follower device remains tilted/offset in the tank and this causes the tank to become inoperable or ineffective and dispensing the material therein. The present invention is directed to remedying this shortcoming.

SUMMARY OF THE INVENTION

The present invention is a modified tank having a pressurizing follower device inside the sealed pressure cylinder, said pressurizing follower device having a lower, body portion, an upper, body portion, the upper body portion and lower body portion being preferably connected together along a circular interface region which is smaller in diameter than the internal cross-sectional diameter of the cylindrical pressure container. Along the interface are four elongate fins that project axially away from the circular interface by approximately the height of the upper body portion of the follower device. These four fins cooperate with the sides of the container to maintain the follower device in a proper orientation when the tank is horizontal and prevents the follower device from tilting when the tank is returned to its vertical orientation. The length of the fins will have a minimum value that will prevent the tipping of the follower device, below which the follower device will still tilt based on the dimensions of the tank and the difference between the follower device's diameter and the tank's diameter.

The invention will best be understood with respect to the figures described below along with the detailed description of the preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view, partially in shadow, of a prior art system;

FIG. 2 is a side view, partially in shadow, of a prior art system;

FIG. 3 is a side view, partially in shadow, of the present invention;

FIG. 4 is a top view of the follower device of FIG. 3;

FIG. 5 is an enlarged, side view of the follower device of FIG. 3; and

FIG. 6 is a bottom view of the follower device of FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 3 illustrates a tank 10 designed to store, transport, and dispense viscous materials, having a tank body 100 that rests upon a stand or base 102. The tank has semi-spherical upper and lower ends 104,106 that are joined to the cylindrical body 100 by annular rings 108. A material ingress/egress port 110 is located at the bottom of the tank 10, and a cap 112 and pressure valve 114 are located on the spherical upper end 104.

FIG. 3 further illustrates an improved ellipsoidal follower device in a grease tank 10 having stabilizing fins 20 that extend longitudinally away from a centerline joining the upper body 30 from the lower body 40 of the follower device 50. The stabilizing fins 20 extend both above and below the centerline 25, although in a preferred embodiment they extend substantially to a height of the upper body 30, but extend only one fourth of that distance below the centerline 25. The presence of the stabilizing fins 20 prevent the follower device 50 from tipping when the tank is laid sideways because the fins 20 keep in contact with the inside wall 60 of the tank 10 and maintain a parallel relationship with the inside wall at all times, no matter what position or angle the tank 10 is placed. There is a critical length L′ of the stabilizing fin 20 that is related to the distance between the diameter D_D of the follower device 50 and the diameter D_T of the tank 10, whereby the angle that the follower device 50 may lean given the tolerance before it will not return to its original position is a function of the weight of the follower device 50, the number of fins 20, the surface roughness R_S of the inner wall 60 of the tank 10, and the internal pressure P_i in the tank. However, it has been found that in most cases a length L that extends to the height of the upper body 30 and twenty five percent (25%) of the depth of the lower body 40 will preserve the orientation of the follower device 50 in virtually all cases and prevent the condition where tipping leads to a non-operational condition.

As shown in FIGS. 5 and 6, the stabilizing fins 20 are thin blade like members (i.e., a depth four times less than a width) that do not interfere with the follower device's function of forcing the material through the tank 10, and further operate as spacers that keep the follower device 50 centered within the tank 10 to protect the tank from marring and damage due to contact with the follower device. The number of stabilizing fins 20 can be increased from four to further stabilize the follower device, although it has been found that four will meet the conditions for stability required in most applications. The fins 20 can be attached by welding in a preferred embodiment, but a small bracket can also be used to fasten the fins 20 to the follower device's centerline 25. It is important that the attachment of the stabilizing fins 20 result in a rigid connection, as any flexure can lead back to the original problem where the follower device tilts excessively and cannot return to its intended orientation. For that reason, the connection of the fins 20 to the follower device 50 must maintain the fins 20 in a tangential relationship with sufficient rigidity to resist bending. To this end, the thickness of the fins must also be of a value to prevent appreciable bending as the tank is laid horizontal, to prevent the follower device from tilting or tipping from the parallel relationship with the longitudinal axis of the tank.

While a preferred embodiment has been described and depicted in the drawings, it is to be understood that the scope of the present invention is not to be limited to the description of the preferred embodiments or the depictions in the drawings. One of ordinary skill in the art would readily appreciate that modifications and substitutions would be available to such described embodiments, and the invention in intended to incorporate and include all such modifications and substitutions. Accordingly, nothing in this specification should be taken as limiting the invention to anything characterized herein unless expressly stated.

Claims

1. A tank for transporting, storing, and dispensing viscous materials having a cylindrical body, and spherical ends, the tank further comprising: an ellipsoidal follower device having an upper half, and lower half, and a centerline;a plurality of stabilizing fins rigidly connected to the ellipsoidal follower device at the centerline and extending axially, the stabilizing fins disposed between a periphery of the ellipsoidal follower device and an inner wall of the cylindrical body;whereby a length of the stabilizing fins is equal to a height of the upper half and quarter depth of the lower half of the ellipsoidal follower device.

2. The tank of claim 1, wherein the stabilizing fins number four and are equally spaced around a perimeter of the ellipsoidal follower device.

3. The tank of claim 2, wherein the stabilizing fins have a depth that is four times less than a width.