American Axle & Mfg Inc v. Neapco DrivELines LLC

1. Case Identification

• Case #: IPR2018-01761
• Patent #: 5,772,520
• Filed: October 11, 2018
• Petitioner(s): American Axle & Manufacturing, Inc.
• Patent Owner(s): Neapco Drivelines LLC
• Challenged Claims: 11 and 12

2. Patent Overview

• Title: Method of Venting a Slip Joint Assembly
• Brief Description: The ’520 patent discloses a method for venting a sealed, splined slip joint in an automotive driveline. The technology is directed at relieving pressure that builds within sealed cavities of the joint during axial movement by providing a vent in one shaft to allow fluid communication from an internal cavity to an area outside the first and second cavities.

3. Grounds for Unpatentability

Ground 1: Anticipation of Claim 11 - Claim 11 is anticipated by Burton under 35 U.S.C. §102(e).

• Prior Art Relied Upon: Burton (Patent 5,655,968).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Burton disclosed every element of claim 11. Burton taught a slip joint assembly with a first male splined shaft and a second female splined shaft having a closed end, which forms a first cavity ("chamber 102"). Burton also disclosed a seal that engages both shafts to create a second cavity ("space 132"). Crucially, Burton described two vent types in the first shaft: non-axial passages (bores 130) and a central axial bore (passage 122), both of which have a first end in fluid communication with one of the cavities and a second end in fluid communication with a location ("chamber 124") outside both the first and second cavities.

Ground 2: Obviousness of Claims 11 and 12 - Claims 11 and 12 are obvious over Burton in view of Rabson, Warner, Yaegashi, and Minel under 35 U.S.C. §103.

• Prior Art Relied Upon: Burton (Patent 5,655,968), Rabson (Patent 3,063,266), Warner (Patent 1,923,649), Yaegashi (Patent 5,771,737), and Minel (FR 2257042).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner asserted that Burton provided the base combination for a vented slip joint as detailed in Ground 1. For the additional limitations of claim 12—providing the vent by creating "an axial bore" and "removing a spline"—Petitioner argued these were well-known and obvious modifications. Rabson and Warner both explicitly taught removing a spline tooth to create a larger passageway for improved venting and lubricant circulation. This directly maps to the "removing a spline" limitation. Burton itself already taught an axial bore vent.
  • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine the teachings of Rabson or Warner with Burton to improve the transfer of air and lubricant, an objective explicitly stated in Burton. Warner taught the combined use of an axial bore and a removed spline for "forced circulation," a highly desirable feature. Additionally, Yaegashi taught removing a spline for "phase-indexing" to ensure proper shaft alignment, providing a second, independent motivation for the same modification. A POSITA would also have been motivated by Minel to modify Burton's vent to exhaust into a larger volume, such as the driveshaft tube, to further minimize pressure variations.
  • Expectation of Success: The combination of these features involved applying conventional and well-established techniques for venting and assembling slip joints. A POSITA would have had a high expectation of success in achieving the predictable result of improved venting and circulation.

Ground 3: Anticipation of Claim 11 - Claim 11 is anticipated by Yoshida under 35 U.S.C. §102(b).

• Prior Art Relied Upon: Yoshida (JP S58-152931).

• Core Argument for this Ground:

  • Prior Art Mapping: Petitioner contended that Yoshida, which describes a universal joint with rolling-element splines, also disclosed all elements of claim 11. Yoshida showed a first male shaft and a second, closed-end female shaft that form a first cavity. It further disclosed a boot seal that engages both shafts, creating a second cavity ("interior a"). A "through-hole 10" in the first shaft served as a vent, extending through the shaft and intersecting with another passageway to provide fluid communication from the second cavity to the exterior, thus venting outside both cavities.

• Additional Grounds: Petitioner asserted an additional obviousness challenge for claims 11 and 12 based on Minel in view of Yoshida, SAE Manual, Rabson, Warner, and Yaegashi, which relied on similar arguments regarding the interchangeability of known spline types and venting arrangements in universal joints.

4. Key Claim Construction Positions

• "vent" (claims 11 and 12): Petitioner proposed that "vent" means "a passageway that permits the transfer of a gas or liquid from a cavity." This construction was argued to be consistent with the specification, which showed venting from one internal cavity to another (e.g., the driveshaft tube), not necessarily to the outside atmosphere. Petitioner noted that during prosecution, the Examiner had accepted similar internal passageways in the prior art as "vents."
• "spline" (claims 11 and 12): Petitioner proposed that "spline" means "any machine element consisting of integral keys (spline teeth) or keyways (spaces) equally spaced around a circle or portion thereof." This construction was intended to be broad enough to encompass not only traditional involute splines but also rolling-element splines, as the patent specification itself suggested its principles could apply to any "plunging splined connection."

5. Arguments Regarding Discretionary Denial

• Petitioner argued that discretionary denial under §325(d) would be inappropriate. The petition asserted that it presented substantial new prior art and arguments that the Patent Office had not previously considered. Specifically, the Examiner did not cite or consider the primary references of Burton, the SAE Manual, Warner, or Yaegashi. Furthermore, the Examiner was not provided with certified English translations of the Japanese Yoshida reference or the French Minel reference, which Petitioner supplied.

6. Relief Requested

• Petitioner requests institution of an inter partes review and cancellation of claims 11 and 12 of Patent 5,772,520 as unpatentable.