Obviousness — US Patent 9518604

Obviousness Analysis of U.S. Patent No. 9,518,604

Introduction

This analysis examines the patentability of the claims in U.S. Patent No. 9,518,604 ("the '604 patent") under 35 U.S.C. § 103, which pertains to obviousness. The '604 patent, titled "Fluid bearings," was filed on June 28, 2013, and claims a priority date of June 28, 2012. Therefore, any prior art considered for this analysis must have been publicly available before this priority date.

The core of the invention as described in the '604 patent relates to fluid bearings, particularly for heavy-duty applications like grinding mills, which utilize a polymer bearing pad mounted on a base. Key features highlighted in the claims include the use of polymer pads, specific mounting mechanisms, the presence of a chamfer on the pad's edge to manage lubricant, and a multi-directional bearing design.

An initial review of the patent's file history and cited references reveals several key prior art documents that, when combined, suggest that the claimed inventions would have been obvious to a Person Having Ordinary Skill in the Art (POSITA). This analysis will focus on combinations of these references to challenge the validity of the independent claims.

Claim 1: Bearing Assembly with Self-Adjusting Polymer Pad Bearings

Claim Language Breakdown:

(a) A bearing assembly for a journal of a grinding mill body.
(b) Comprising a frame and a plurality of fluid bearings.
(c) Each fluid bearing comprises a polymer bearing pad mounted to a base.
(d) The polymer bearing pad has an outer surface and at least one recess for receiving and distributing lubricating fluid.
(e) The base has a lubricating fluid supply port and a passage in fluid communication with the recess.
(f) The base is mounted to the frame so that the fluid bearings self-adjust to changes in the angular position of the journal.

Obviousness Combination:

A compelling case for the obviousness of claim 1 can be constructed by combining the teachings of U.S. Patent No. 4,362,342 (Simmons) and GB Patent Application No. 2,382,148 (Glacier Penco).

Simmons (US 4,362,342): Published in 1982, Simmons discloses a tilting pad thrust bearing assembly. Crucially, Simmons teaches the use of bearing pads made from a polymeric material, specifically polyetheretherketone (PEEK), which is one of the preferred materials mentioned in the '604 patent specification (Col. 9, ln. 22-26). Simmons describes how these polymer pads are mounted on a carrier and can be replaced individually (Simmons, Abstract; Col. 2, lines 52-59). The bearing pads in Simmons are designed to receive lubricating fluid.
Glacier Penco (GB 2,382,148): Published in 2003, this document describes a hydrostatic bearing assembly specifically for large rotating machinery like grinding mills. It explicitly teaches a self-aligning bearing arrangement where bearing pads are mounted on spherical seats to allow them to adjust to the angular position of the journal (Glacier Penco, Page 3, lines 1-10; Figures 1 & 2). The bearings described are fluid bearings with recesses for distributing high-pressure oil.

Motivation to Combine:

A person of ordinary skill in the art (POSITA) at the time of the invention would have been familiar with both hydrostatic bearing designs for heavy machinery (as in Glacier Penco) and the use of advanced polymer materials for bearing surfaces (as in Simmons).

The motivation to combine these teachings would stem from the well-known desire to improve the reliability, durability, and maintainability of bearings in demanding environments like grinding mills. The '604 patent itself highlights the problems of prior art metal bearings, such as damage from loss of oil pressure and costly repairs (Col. 2, ln. 1-14).

A POSITA, aware of the self-lubricating and damage-tolerant properties of polymers like PEEK from Simmons, would have found it obvious to replace the traditional metallic bearing pads in a self-aligning hydrostatic system like the one in Glacier Penco with these superior polymer pads. This combination would directly address the wear and damage issues associated with metal-on-metal contact during events like a power failure. The replacement of one known bearing surface material (metal) with another known bearing surface material (polymer) to achieve predictable improvements in wear resistance and damage tolerance would be considered an obvious design choice.

Therefore, the combination of Glacier Penco's self-aligning bearing assembly for mills with Simmons's teaching of replaceable polymer bearing pads renders the subject matter of claim 1 obvious.

Claim 11: Method of Making a Polymer Bearing Pad

Claim Language Breakdown:

(a) Forming a polymer pad with an outer surface.
(b) Forming at least one recess in the pad for receiving and distributing lubricating fluid.
(c) Forming a mounting means on the pad for secure attachment to a base.

Obviousness Combination:

This claim is directed to the method of manufacturing the polymer pad. The steps described are fundamental manufacturing processes that would be obvious in light of the state of the art. The teachings of Simmons (US 4,362,342), in combination with general engineering knowledge, render this claim obvious.

Simmons (US 4,362,342): As established, Simmons teaches the use of a polymer (PEEK) bearing pad. The figures in Simmons (e.g., Fig. 2) clearly show a pad (12) with a bearing surface and a method of securing it to a carrier (13). The '604 patent describes forming the pad by heating and molding a polymer sheet, or by machining it (Col. 8, ln. 3-30). These are standard and well-known techniques for shaping polymer materials.
General Engineering Knowledge: The steps of forming a recess (e.g., by milling or molding) and forming a mounting means (e.g., by machining a protrusion or drilling a hole) are elementary manufacturing steps. Once a designer decides to create a polymer bearing pad, as taught by Simmons, the subsequent steps of shaping it, creating fluid distribution channels, and providing for its attachment are dictated by functional requirements and would be implemented using standard, well-understood manufacturing techniques. The '604 patent itself describes these steps as common methods like machining, drilling, punching, or molding (Col. 8, ln. 26-30).

Motivation to Combine:

The motivation here is simply to produce the article disclosed in Simmons. Simmons discloses a polymer bearing pad for a fluid bearing application. A POSITA tasked with manufacturing such a pad would inherently need to perform the steps of forming the pad's basic shape, creating any necessary features for lubrication (recesses), and creating features to mount it. These steps are not an inventive process but a logical and routine sequence of manufacturing operations. Therefore, claim 11 is obvious over Simmons combined with the general knowledge of a person skilled in the art of mechanical and polymer engineering.

Claim 23: Fluid Bearing with a Chamfered Polymer Pad

Claim Language Breakdown:

(a) A fluid bearing for a journal.
(b) A base with a lubricating fluid supply port and passage.
(c) A polymer bearing pad mountable to the base, with a recess.
(d) The polymer pad further comprising a chamfer at an outer edge for retaining and transferring lubricating fluid to the journal.

Obviousness Combination:

The key feature of this claim is the "chamfer" on the polymer pad's edge. This feature would be obvious to a POSITA based on the teachings of U.S. Patent No. 5,161,894 (Ide) combined with Simmons (US 4,362,342).

Ide (US 5,161,894): Published in 1992, Ide is directed to improving the lubrication of sliding bearings. It explicitly teaches the creation of a tapered or chamfered "lead-in" section at the edge of a bearing pad (Ide, Fig. 2, element 5; Col. 3, lines 40-50). The stated purpose of this chamfer is to facilitate the formation of a hydrodynamic oil film, especially at startup or low speeds, by helping to draw oil between the bearing and the shaft. This is precisely the function attributed to the chamfer in the '604 patent, which describes it as creating a "lead-in and lead-out for the oil" (Col. 7, ln. 35-37).
Simmons (US 4,362,342): Simmons, as previously discussed, teaches the use of polymer for the bearing pad material.

Motivation to Combine:

A POSITA, starting with the polymer bearing pad taught by Simmons, would be motivated to improve its lubrication characteristics, particularly in the high-load, low-speed conditions experienced by grinding mills during startup and shutdown. The problem of maintaining a lubricating film in such conditions is a well-known challenge in bearing design. Ide provides a direct and explicit solution to this problem by introducing a chamfer at the leading edge of the bearing.

It would have been an obvious step for a skilled artisan to apply the known lubrication-enhancing feature from Ide (the chamfer) to the polymer bearing pad of Simmons to improve its performance. The combination is a simple substitution of one known bearing material for another in a known bearing geometry, with the predictable result of improved hydrodynamic lubrication and oil retention, as described in both Ide and the '604 patent. The combination of Ide and Simmons thus renders the invention of claim 23 obvious.

Claim 27: Multidirectional Fluid Bearing

Claim Language Breakdown:

(a) A multidirectional fluid bearing for a journal.
(b) A base with a first surface orthogonal to a second surface, and a fluid supply.
(c) A first polymer pad on the first surface (acting as a radial bearing).
(d) A second polymer pad on the second surface (acting as an axial bearing).

Obviousness Combination:

This claim describes a combined radial and axial bearing using polymer pads. Such a configuration is rendered obvious by combining the teachings of U.S. Patent No. 4,496,251 (Krysiak) with Simmons (US 4,362,342).

Krysiak (US 4,496,251): Published in 1985, Krysiak discloses a hydrodynamic bearing assembly that is specifically designed to handle both radial and axial (thrust) loads. The figures in Krysiak clearly show bearing elements arranged to support a shaft both radially and axially from a single integrated structure (Krysiak, Fig. 1). The bearing surfaces are provided with recesses for lubricant distribution.
Simmons (US 4,362,342): Simmons teaches the advantages of using polymer pads in bearing applications.

Motivation to Combine:

A POSITA seeking to improve the performance of a combined radial-axial bearing like that shown in Krysiak would be motivated to incorporate more advanced materials to reduce friction, wear, and the risk of seizure. As discussed previously, the benefits of using polymer bearing surfaces were known from references like Simmons.

It would have been obvious to a designer to take the integrated radial-axial bearing structure of Krysiak and replace the conventional bearing surfaces with the polymer pads taught by Simmons. This would be a straightforward application of a known material (polymer pads) to a known bearing configuration (a combined radial/axial bearing) to achieve the expected benefits of improved durability and performance. This combination of known elements for their predictable purposes renders claim 27 obvious.