PTAB

IPR2017-01497

Toyota Motor Corp v. Intellectual Ventures II LLC

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1. Case Identification

2. Patent Overview

  • Title: Stator Assembly Made from a Molded Web of Core Segments and Motor Using Same
  • Brief Description: The ’952 patent discloses a stator assembly for an electric motor constructed from a plurality of discrete arc segments. The segments are at least partially encased in a "phase change material" (e.g., thermoplastic) which also forms a "bridge" with two interconnecting mating sections to link the segments into a continuous strip for assembly.

3. Grounds for Unpatentability

Ground 1: Claims 10-12 are obvious over Nakahara in view of Ishihara and/or Lieu.

  • Prior Art Relied Upon: Nakahara (Japanese Patent No. 07-245895), Ishihara (Japanese Patent No. 11-089128A), and Lieu (WO 01/45233).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Nakahara taught a stator assembly with discrete segments encased in thermoplastic coil bobbins linked into a continuous strip by flexible, single-piece "thin parts." The key missing limitation—a bridge formed by interconnecting two mating sections—was explicitly supplied by Ishihara. Ishihara identified Nakahara as prior art and proposed an improvement to solve manufacturing drawbacks by replacing Nakahara’s single-piece links with two-part, freely pivoting "connection members" (e.g., a hinge joint) that mate to join adjacent bobbins. For dependent claim 11, Nakahara taught overmolding a stator with resin, and Lieu taught the specific benefits of using a thermoplastic material for this purpose, making the substitution obvious. For dependent claim 12, Nakahara’s “outer yoke” met the “retaining member” limitation.
    • Motivation to Combine: A POSITA would combine Nakahara and Ishihara because Ishihara expressly identified problems with Nakahara’s design (e.g., requiring large molding dies) and provided a specific solution: replacing the single-piece flexible bridge with two-part mating connection members. A POSITA would combine this with Lieu to gain the known advantages of thermoplastic overmolding, such as improved heat dissipation and reduced vibration.
    • Expectation of Success: Success was expected because Ishihara was designed as a direct improvement upon the very structure disclosed in Nakahara. The references were highly analogous, both depicting hexagonal stators with segments fitted into coil bobbins, making the integration of Ishihara's mating connectors into Nakahara's design predictable.

Ground 2: Claims 10-12 are obvious over Iikuma in view of Nakahara, Lieu, and/or Stridsberg.

  • Prior Art Relied Upon: Iikuma (Japanese Patent No. 1997-308163), Nakahara (Japanese Patent No. 07-245895), Lieu (WO 01/45233), and Stridsberg (WO 95/12912).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner asserted that Iikuma disclosed all limitations of claim 10 except for the use of a "phase change material." Iikuma taught a segmented stator where insulators on each segment featured an "engaging arm" with a hook portion that mated with a "channel" on an adjacent insulator. This hook-and-channel structure formed a bridge by interconnecting two mating sections. The combination with Nakahara rendered it obvious to form Iikuma’s insulators from a phase change material, as Nakahara taught using thermoplastics (e.g., nylon, polypropylene) for analogous insulators. For claim 11, Iikuma taught overmolding with an "insulating resin," and Lieu made it obvious to use a thermoplastic for this purpose. For claim 12, Iikuma’s "wiring plate" was a retaining member; alternatively, Stridsberg taught using a shrink-fit outer ring to retain stator segments, which was analogous to the ’952 patent's collar.
    • Motivation to Combine: A POSITA would combine Iikuma with Nakahara as a matter of simple material substitution. Since Iikuma did not specify its insulator material, a POSITA would consult analogous art like Nakahara and find known, suitable thermoplastics for the application. The motivation to add Stridsberg was to provide a more robust retaining member than Iikuma’s wiring plate, achieving benefits like reduced magnetic losses and precise segment alignment.
    • Expectation of Success: Success was expected due to the similarities in the designs. Both Iikuma and Nakahara showed methods of encasing segmented stator cores with insulators, making the application of Nakahara’s material choice to Iikuma’s structure straightforward and predictable.

Ground 3: Claims 10-12 are obvious over Sheeran in view of Nakahara and/or Lieu.

  • Prior Art Relied Upon: Sheeran (Patent 7,471,025), Nakahara (Japanese Patent No. 07-245895), and Lieu (WO 01/45233).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Sheeran, like Iikuma, disclosed all elements of claim 10 except for the specific material choice. Sheeran taught a "rack-of-ribs" style stator assembly where segments were encased in flexible plastic containment structures. To form the final annular stator, Sheeran disclosed engagement/locking structures (a projection and a receptive element with a latching finger) on opposing ends of the strip. These structures constituted a bridge formed by interconnecting two mating sections. The combination with Nakahara rendered it obvious to make Sheeran's plastic containment structures from a "phase change material." For claim 11, although Sheeran did not teach overmolding, Petitioner argued this feature was admitted to be well-known and that Lieu made the use of a thermoplastic material for this purpose obvious. For claim 12, Sheeran’s disclosure of using an encircling "band" to hold the assembly in its annular shape met the "retaining member" limitation.
    • Motivation to Combine: A POSITA would be motivated to use the thermoplastic materials of Nakahara for the plastic containment structures in Sheeran because Sheeran did not specify a particular plastic, and Nakahara provided suitable, well-known options for the same purpose (insulating stator segments). A POSITA would combine this with Lieu to incorporate the known benefits of overmolding, a technique Sheeran suggested as a possible retention method.
    • Expectation of Success: The combination was expected to succeed because it involved substituting a known material (from Nakahara) for a known purpose (insulation) into a similar device (Sheeran), which is a predictable modification.

4. Key Claim Construction Positions

  • "phase change material": Petitioner argued this term should be construed broadly to mean "a material that can be used in a liquid phase to envelop[] the stator, but which later changes to a solid phase." This construction encompasses thermoplastics, thermosetting materials, and epoxies, which Petitioner showed were common in the prior art for encasing stator components.
  • "a bridge between adjacent segments to link adjacent segments into a continuous strip": Petitioner contended this phrase means the strip is continuous in a lengthwise (peripheral) direction. This construction was based on the patent’s figures and preferred embodiment, which consistently show a lengthwise strip.
  • "the bridge is formed by interconnecting two mating sections": Petitioner argued this product-by-process limitation is satisfied if the prior art bridge comprises two interconnected mating sections, regardless of the specific manufacturing step used to form them. This was consistent with the examiner’s reasoning during prosecution.