WO2001001004A1

WO2001001004A1 - Self-lubricating omni-directional ball transfer mechanism

Info

Publication number: WO2001001004A1
Application number: PCT/US2000/017928
Authority: WO
Inventors: Christopher John Sommers
Original assignee: Roller Bearing Company Of America, Inc.
Priority date: 1999-06-29
Filing date: 2000-06-29
Publication date: 2001-01-04

Abstract

There is provided a rolling vehicle having a frame (15), at least one ball transfer mechanism (10) fixedly attached to the underside of the frame, the ball transfer mechanism having a housing (12), a sphere (18) rotatably held in the housing, and a self lubricator (20) for maintaining the rotatable movement of the sphere.

Description

SELF-LUBRICATING OMNI-DIRECTIONAL BALL TRANSFER MECHANISM

Technical Field

The present invention relates to a ball transfer mechanism. Additionally, the present invention relates to a self-lubricating, omnidirectional ball transfer mechanism.

Background of the Invention

A ball-transfer mechanism is a roller device which allows a vehicle to move in any direction relative to a generally level surface. Such a ball- transfer mechanism has a structure, for example, utilizing small balls to allow the ball-transfer mechanism to function. Examples of ball castors and ball transfer units are described in United States Patents 3,557,401 to Castors; 3,577,520 to Hoffman; 3,739,894 to Hinman; 3,744,083 to Jenkins; and 4,696,583 to Gorges. The ball-transfer mechanism is used, for example, as one of several wheels on an industrial flat car which is movable in any direction on a generally level surface. A large ball which contacts the level surface is configured to roll in any direction while supported by a main body. The ball-transfer mechanism includes the main body and a supporting member disposed within the main body. A space is defined between the supporting member and an inner portion of the main body. An upper portion of the space has a generally spherical shape, with lower portions of the space having an annular shape open to the portion of the main body where the large ball is located.

A plurality of small balls are retained within the space between the supporting member and the large ball. The small balls may roll around edges of the supporting member such that the small balls are freely disposed between the supporting member and about an enclosed portion of the large ball.

The small balls follow the rolling movement of the large ball and must with stand forces associated with the loads acting on the large ball. In other words, the small balls provide support for the ball-transfer mechanism, allowing the large ball to rotate in various directions within the main body while retarding friction between the large ball and the housing.

When a small ball enters the space, the small ball no longer receives the loads or forces from the large ball. Within the space, the primary force acting on the small balls is gravity. Therefore, within the space, the small balls naturally tend to move downward and further tend to move toward areas where the least number of other small balls are located. For example, the small balls can easily move to an opposite side of a center axis, resulting in allowing the large ball to roll inside the main body.

When a ball transfer mechanism, such as that described above, is used, there are included many small parts. These small parts can become a hazard if they become loose. This creates the potential for undesired objects to enter the space between the supporting member and the large ball which potentially inhibits movement of the ball transfer mechanism. It is this inhibition that creates a likelihood that these parts can become contaminated and thus shorten the life of the part and/or freeze the mechanism.

It would therefore be useful to design a low cost, lightweight ball transfer mechanism. It would also be useful to design a ball transfer mechanism which does not include therein multiple loose parts. Summary of the Invention

According to the present invention, there is provided a ball transfer mechanism including a housing, a sphere which is rotatably held in the housing, and a self-lubricating material disposed between the sphere and housing which maintains the rotatable movement of the sphere. Also provided is a rolling vehicle including a frame, at least one ball transfer mechanism fixedly attached to the underside of the frame. The ball transfer mechanism includes a housing. A sphere is rotatably held in the housing. A self lubricating material is disposed between the sphere and housing for maintaining the rotatable movement of the sphere.

Brief Description of the Drawings

Other advantages of the present invention will be readily appreciated

as the same becomes better understood by reference to the following detailed

description when considered in connection with the accompanying drawing

wherein:

FIGURE 1 is a cross-sectional view of the preferred embodiment of the present invention.

Detailed Description of the Preferred Embodiment

Generally, the present invention provides a ball transfer mechanism, shown generally at 10. The mechanism 10 includes a housing generally indicated at 12.

The housing 12 includes a base portion 13 for connection to frame 15. The frame 15 can be in any form, such as a cart or other vehicle commonly used for transferring loads. The housing 12 can be bolted or otherwise fixedly secured to the frame 15. The housing 12 can be made from any durable material as known in the art. This material can include, but is not limited to wood, composite materials, or phenolic castings.

The housing 12 includes a casing portion 17 for containing a carrier block 16 and large sphere 18 therein. The sphere 18 can be of any type well known in the art, preferably made from a durable metal or, for lighter loads, a plastic. Flanges 19, 21 surround and encase or trap the carrier block 16 and sphere 18 within the casing portion 17. The carrier block materials may be any solid material whose physical strength properties meet the application requirements. Additional consideration may include weight, fluid/environmental compatability, and temperature. All metallic and non- metallic materials may be candidates, including steel, aluminum, titanium, zinc die castings, or molded plastics, i.e. glass filled nylon.

It should be noted that the housing 12 can be made in other configurations well known in the art or otherwise. For example, the housing 12 can be supplied by the structure which requires the sphere 18 in order to operate.

The sphere 18 is rotatably held in the housing 12. A self-lubricating material 20 maintains the rotatable movement of the sphere 18 vis-a-vis the carrier block 16.

More specifically, the sphere 18 is configured for rolling engagement with a generally flat surface. Preferably, the housing 12 is formed with a cylindrically shaped casing portion 17 having a substantially closed first end 23, and an opposing open end 25 and a cylindrical wall 27 extending therebetween. The carrier block 16 is disposed within the housing 12 trapped between the flanges 19, 21 and within the cylindrical wall 27. The carrier block 16 has first and second surfaces 29, 31. The first surface 29 has a generally convex shape forming a seating surface. The second surface 31 fits within the housing 12 and is held in place by the housing 12.

The carrier block 16 can perform two different functions. First, the carrier block 16 and housing 12 can be designed for sphere 18 retention as set forth above. In another embodiment of the present invention, the carrier block 16 is designed such that the carrier block 16 is capable of being installed into a separate structure. This structure can include, but is not limited to, the structure to which the ball transfer mechanism is being attached.

The housing 12 and carrier block 16 can include a drain hole 14 extending thereon. As mentioned previously, the carrier block 16 has a generally concave surface 24 forming a seating surface. This surface is configured to accept the large sphere 18. Between the large sphere 18 and the surface 29 of the carrier block 16 is the self lubricating material 20. More specifically, the self lubricating material 20 contacts and supports the large sphere 18 such that there is sufficient lubrication between the self-lubricating material 20 and the large sphere 18 to enable a uniform rotational motion of the sphere 18. This sphere 18 enables the object to which the ball transfer mechanism 10 is attached to move in a uniform manner without any jerkiness or sudden movements. The self lubricating material 20 is made of an antifriction material in the form of a film thus maintaining universal and continuous motion of the large sphere 18. The film can be made from carbon fibers and matrices, molybdenum disulfide, polytetrafluoroethylene, fluoroethylene- propylene copolymer, niobium diselenide and tungston disulfide. The list herein is meant to be exemplary. Any material used must have sufficient load bearing capability, good overall lubricating strength while not significantly promoting metal corrosion. In order to minimize friction and wear, the lubricant should provide low shear strength, strong adhesion to a substrate material, good malleability, complete surface coverage where applied and freedom from abrasion impurities. These can include inorganic compounds and bonded solid-film lubricants.

Preferably, the self-lubricating material 20 is disposed on a metal backing 22. The metal backing 22 is operatively connected, as by glue or other means known in the art, to the seating surface 29 of the carrier block 16. Alternatively, the block 16 and self-lubricating material 20 can be sized so as to not require absolute fixing. Rather, the flanges 19 contain the components in position.

A wiper 24 can be disposed about the flange 19 to prevent dust and other particles from entering between the sphere 18 and self-lubricating material 20.

When assembling the ball transfer mechanism 10 from the above described parts, the assembly 10 is carried out as depicted in the Figure. First, the housing 12 is assembled, then the carrier block 16 is inserted therein. The self-lubricating material 20 is then added to the carrier block 16 in the appropriate position. Finally, the large sphere 18 is put in place. This is installed and held in place via the housing member 12. However, the orientation of the mechanism 10 is irrelevant. Thus, the sphere 18 can be installed such that the ball is located on the top, on the bottom or side of the mechanism 10. Since there are no small balls utilized in the present invention, there are no limitations with regard to orientation.

When the ball transfer mechanism 10 is in its operating condition, the large sphere 18 and self lubricating material 20 are retained within the ball transfer mechanism 10, because the inner diameter of the lower part of the sphere 18 is smaller than the diameter of the housing 12 opening thus preventing the large sphere 18 from moving outside of the housing 12. The self lubricating material 20 is such that it enables the large sphere 18 fluid movement within the housing 12. In other words, when the ball transfer mechanism 10 is in contact with the floor, the large sphere 18 is supported by the self lubricating material 20 within the housing 12, not only in the vertical direction, but also in directions generally parallel to the surface of the floor.

When moving an industrial flat cart, for example, or other rolling vehicle which uses a plurality of ball transfer mechanisms 10, four ball transfer mechanisms 10 serve as wheels and the flat cart rolls freely. In this state, the ball transfer mechanisms 10 allow the large spheres 18 to freely rotate. The industrial flat cart moves while the large spheres 18 roll supported by the housing 12. When the large spheres 18 roll, the self lubricating material 20, which abuts the upper circumferential face of the large sphere 18, moves against the supporting face of the carrier block 16. As the self lubricating material 20 enables fluid movement, the industrial flat cart can continue to move smoothly since the large sphere 18 can continue to easily roll within the housing 12.

The invention has been described in an illustrative manner, and it is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

Claims

CLAIMSWhat is claimed is:

1. A ball transfer mechanism comprising: a housing; a sphere rotatably held in said housing; and self-lubricating means disposed between said housing and said sphere for maintaining the rotatable movement of said sphere.

2. The ball transfer mechanism according to claim 1 , wherein said housing includes an outer frame and at least one carrier block fixedly contained within said outer frame, said carrier block includes a seating surface supporting said self lubricating means.

3. The ball transfer mechanism according to claim 2, wherein said housing and self lubricating means include a drain hole extending therethrough.

4. A ball transfer mechanism according to claim 1 wherein said self lubricating means includes a self material operatively connected to a backing material, said backing material being operatively connected to said carrier block.

5. A ball transfer mechanism according to claim 4, wherein said self lubricating material is selected from the group consisting of solid film lubricants.

6. A ball transfer mechanism according to claim 5, wherein said self lubricating material is selected from the group consisting of carbon fibers and matrices, molybdenum disulfide, polytetrafluoroethylene, fluoroethylene- propylene copolymer, niobium diselenide, and tungston disulfide.

7. A rolling vehicle comprising: a frame; at least one ball-transfer mechanism fixedly attached to the underside of said frame, said ball transfer mechanism comprising: a housing; a sphere rotatably held in said housing; and self-lubricating means disposed between said housing and said sphere for maintaining the rotatable movement of said sphere.