Patent Application
20110170811
The present invention relates to systems and methods for controlling interaction between surfaces. More specifically, the present invention concerns a system and method for controlling interaction, i.e., interpenetration, between first and second surfaces by arranging or designing the surfaces such that the repetitive surface geometries, or “asperities,” of the surfaces are in particular relative ratios.
When interacting surfaces move relative to each other, friction between the surfaces converts kinetic energy to heat and can abrade one or both of the surfaces. In some applications, it is desirable to minimize such interactions.
The coefficient of friction is a dimensionless scalar vector describing the ratio of the force of friction between two surfaces and the force bringing them together. A lower coefficient of friction corresponds to less interaction between the surfaces. Coefficients of friction must be measured experimentally as they cannot be calculated.
Interaction between surfaces is often controlled by selecting materials which result in the desired coefficient of friction. However, in many applications, specific materials must be used, and therefore friction cannot be controlled by using different materials. Interaction between surfaces is also often controlled by interposing a lubricating or abrading substance between the surfaces. However, in some applications these additional substances cannot be used, because, for example, they create an unacceptable risk of contamination, and in other applications the substances do not remain consistently interposed between the surfaces.
The present invention overcomes the above-described and other problems and disadvantages by providing a system and method for reducing interaction between surfaces moving relative to each other.
In one embodiment, the system broadly comprises a first surface having a first number of repetitive surface asperities per unit length of surface; and a second surface having a second number of repetitive surface asperities per unit length of surface, wherein the first and second numbers are in relative prime ratio, i.e., have no common divisor other than 1, and wherein the first and second surfaces move relative to each other. In one exemplary implementation, the first number is approximately 11 and the second number is approximately 13.
In one embodiment, the method broadly comprises the steps of providing the first surface with a first number of repetitive surface asperities per unit length of surface; and providing the second surface with a second number of repetitive surface asperities per unit length of surface, wherein the first and second numbers are in relative prime ratio. In one implementation, the first number may be approximately 11 and the second number may be approximately 13. In various implementations, the ratio of asperities may be controlled as a function of component particle or grain size, groove size, or relative angular orientation of the surfaces.
These and other features of the present invention are described in greater detail below in the section titled Detailed Description of the Invention.
The present invention is described herein with reference to the following drawing figures:
With reference to the drawing figures, a system and method are herein described, shown, and otherwise disclosed in accordance with various embodiments, including a preferred embodiment, of the present invention.
More specifically, the present invention provides a system and method for controlling interaction, i.e., interpenetration, between surfaces, and thereby controlling friction, heat, and abrasive wear between the surfaces. The system and method are scale independent, and, as such, have potential applications at, e.g., atomic, molecular, nanomachine, conventional mechanical, and geologic scales. For example, potential applications include minimizing friction, heat, and abrasive wear in unlubricated bearings and in lubricated bearings where the lubricant fails to fully and continuously support the load.
Broadly, referring to
“Relative prime ratio” means that the first and second numbers share no common divisors other than 1. Thus, for example, the first and second numbers may both be prime numbers, such as 7:11 or 17:19, or one of the numbers may be prime and the other number may be any number which has no common divisors with the first number (other than 1), such as 8:11 or 16:19, or neither of the numbers may be prime so long as there are no common divisors between them (other than 1), such as 9:10 or 15:16.
For certain applications, a relative prime ratio of 11:13 may provide 30 maximum support with minimum interpenetration. In this example, unit length of surface corresponds to the distance between the 1st and 11th asperities of the first surface 10 (which is equivalent to the distance between the 1st and 13th asperities of the second surface 12). As such, there is only one point of contact, i.e., one point at which an asperity 14 of the first surface 10 aligns with and contacts an asperity 16 of the second surface 12, over the unit length of surface. Additionally, the 5th and 6th asperities provide intermediate support during the transition between contacting asperities when the surfaces 10,14 are moving relative to one another.
Referring to
Referring to
For certain scales or materials, e.g., ceramics and metals, these relative asperity ratios can be controlled as a function of component particle or grain size, while 10 for other scales or materials, e.g., machined materials, these ratios can be controlled as a function of groove size.
Potential applications for the present invention include reducing friction in or between piston rings and cylinder walls; gears; linear and non-linear bearings and journals; telescoping mechanisms; scroll compressors; engines; and pumps. Furthermore, the present invention may be used in both unlubricated and lubricated applications.
For some applications it may be desirable to increase or decrease interaction at one scale, and do the opposite at another scale. For example, it may be desirable to decrease interaction at a relatively large scale between a piston ring and a cylinder wall so as to minimize large scale friction, and increase interaction at a relatively small scale so as to more quickly accomplish seating the ring. Thus, on a relatively large scale, the ring and wall surfaces would appear substantially as shown in
In some applications, at least one of the materials presenting the first and second surfaces 10,12 may be non-solid. For example, in some applications, the first surface 10 may be a solid, and the second surface 12 may comprise molecules of a liquid or gas such that they behave substantially as a solid surface adjacent to the first surface 10. In one such application, the first surface 10 may be a chute, and the second surface 12 may comprise grains of sand flowing down the chute. In another of such applications, the first surface 10 may be a pipe, and the second surface 12 may comprise a liquid or gas under pressure flowing through the pipe.
Although the present invention has been disclosed with reference to particular embodiments, implementations, versions, and features it is understood that equivalents may be employed and substitutions made herein without departing from the contemplated scope of protection.
Having thus described the preferred embodiment of the invention, what is claimed as new and desired to be protected by Letters Patent includes the following:
The present U.S. non-provisional patent application claims priority of a previously filed and co-pending U.S. provisional patent application having the same title, Ser. No. 61/074,310, filed Jun. 20, 2008. The identified previously filed application is hereby incorporated by reference into the present application.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US2009/048019 | 6/19/2009 | WO | 00 | 3/23/2011 |
| Number | Date | Country | |
|---|---|---|---|
| 61074310 | Jun 2008 | US |
