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CAFC-PTOAugust 18, 2026·2025-1455, 2025-1456·Affirmed.

Robert Bosch LLC v. Westport Fuel Systems Canada Inc.

Patent Trial and Appeal Board

Holding

The Federal Circuit affirmed the Board’s finding that Bosch failed to prove Klügl disclosed the disputed limitation requiring the hydraulic fluid to act substantially as a solid with substantially constant thickness during activation. Substantial evidence supported the Board’s reliance on Klügl’s repeated description of membrane 6 as flexible and its credibility assessment discounting Bosch’s expert testimony.

Why It Matters

The decision reinforces that IPR petitioners must tie each limitation to record-supported prior-art teachings in the petition and cannot overcome contrary express disclosures with conclusory expert or attorney argument.

Full Summary

Robert Bosch LLC v. Westport Fuel Systems Canada Inc. The Federal Circuit affirmed the Board’s finding that Bosch failed to prove Klügl disclosed the disputed limitation requiring the hydraulic fluid to act substantially as a solid with substantially constant thickness during activation. Substantial evidence supported the Board’s reliance on Klügl’s repeated description of membrane 6 as flexible and its credibility assessment discounting Bosch’s expert testimony. The decision reinforces that IPR petitioners must tie each limitation to record-supported prior-art teachings in the petition and cannot overcome contrary express disclosures with conclusory expert or attorney argument. Affirmed. The disputed limitation required a passive hydraulic link in which hydraulic fluid acts substantially as a solid and maintains substantially constant thickness while the actuator is activated. Bosch relied on Klügl for that limitation, but the Board found Klügl’s membrane 6 was expressly and repeatedly described as flexible, meaning the fluid would change shape rather than act as a solid. The Federal Circuit held that substantial evidence supported the Board’s finding, including Westport’s expert testimony and Klügl’s own disclosures referring to membrane 6 as a flexible membrane in the relevant embodiments. The court also upheld the Board’s decision to give reduced weight to Bosch’s expert testimony as incomplete and contradictory. To the extent Bosch tried to rely on Wirbeleit for the disputed limitation on appeal, the court found no abuse of discretion in the Board’s view that the petition relied solely on Klügl for that point. § 103 waiver / forfeiture non-precedential § 103 waiver / forfeiture non-precedential § 103 waiver / forfeiture non-precedential

Key Points

  • The disputed limitation required a passive hydraulic link in which hydraulic fluid acts substantially as a solid and maintains substantially constant thickness while the actuator is activated.
  • Bosch relied on Klügl for that limitation, but the Board found Klügl’s membrane 6 was expressly and repeatedly described as flexible, meaning the fluid would change shape rather than act as a solid.
  • The Federal Circuit held that substantial evidence supported the Board’s finding, including Westport’s expert testimony and Klügl’s own disclosures referring to membrane 6 as a flexible membrane in the relevant embodiments.
  • The court also upheld the Board’s decision to give reduced weight to Bosch’s expert testimony as incomplete and contradictory.
  • To the extent Bosch tried to rely on Wirbeleit for the disputed limitation on appeal, the court found no abuse of discretion in the Board’s view that the petition relied solely on Klügl for that point.
§ 103waiver / forfeiturenon-precedential