PTAB

IPR2013-00096

Honeywell Intl Inc v. HVAC Modulation Technologies LLC

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1. Case Identification

2. Patent Overview

  • Title: CONTROL METHODS AND APPARATUS FOR GAS-FIRED COMBUSTORS
  • Brief Description: The ’642 patent discloses a general control system for gas-fired combustors, such as furnaces and boilers. The system is designed for responsive operation beyond fixed settings by variably controlling the gas input rate, combustion air input rate, and circulation air rate to continuously balance heat supply with changing heating loads.

3. Grounds for Unpatentability

Ground 1: Anticipation over the GRI Reference - Claims 1-4, 6-7, 9-12, 14-15, and 19-22 are anticipated under 35 U.S.C. §102 by the GRI Reference.

  • Prior Art Relied Upon: Feldman et al., "Modulating Furnace and Zoned Heating System Development," GRI-91/0075 (Jan. 1991) (“GRI Reference”).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that the GRI Reference, a publication from the patent’s original assignee (Gas Research Institute), disclosed every limitation of the independent claims. During a prior ex parte reexamination, the claims were deemed patentable because the cited art allegedly failed to teach a "modulating blower for modulating the supply of combustion air." Petitioner asserted the GRI Reference directly contradicts this finding by explicitly describing a furnace system where the combustion gas, circulating air, and combustion air are all continuously modulated over a wide range. The reference specifically taught using an ECM (electrically commutated motor) to drive the inducer blower for combustion air modulation, which was the very feature that secured patentability in reexamination. Furthermore, the GRI Reference disclosed using a pulse-width-modulating valve for gas flow and an ECM-driven fan for circulating air, matching other key limitations of the challenged apparatus and method claims.

Ground 2: Obviousness over GRI in View of Secondary Art - Claims 16, 17, 18, and 23 are obvious under 35 U.S.C. §103 over the GRI Reference in view of various secondary references.

  • Prior Art Relied Upon: Primary: GRI Reference. Secondary: Rheem 1 (“New Imperial Gas Furnace” brochure, 1970), Rheem 2 (“Solid State Breakthrough” brochure, 1969), Patent 3,967,614 (’614 patent), and Patent 4,607,787 (’787 patent).

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner contended that to the extent certain dependent and independent claim limitations were not explicitly disclosed in the GRI Reference, they were well-known in the art and combining them would have been obvious.
      • For claim 16, which adds monitoring temperature at the heat exchanger, Petitioner argued the GRI Reference itself contemplated this but deemed it unnecessary. Alternatively, Rheem 1 and Rheem 2 both taught using a thermistor or solid-state sensor at the heat exchanger to control the circulating blower and maintain a constant supply air temperature.
      • For claims 17 and 23, which add monitoring temperature in the return air conduit, the ’787 patent taught a control system that measures the temperature differential between supply and return air ducts to improve furnace efficiency.
      • For claim 18, requiring an input signal from a sensor adjacent to the heat source to modulate fuel flow, the ’614 patent taught a furnace that uses a temperature sensing probe to monitor temperature and adjust the input fuel rate accordingly.
    • Motivation to Combine: A person of ordinary skill in the art (POSITA) would combine these known features with the GRI furnace to achieve predictable benefits. For instance, a POSITA would integrate the temperature sensor from Rheem into the GRI system to gain the known advantage of maintaining a constant supply air temperature, which the Rheem brochure advertised as ending "'hot-nose, cold-feet' heating." Similarly, incorporating the return-air sensor from the ’787 patent would be a straightforward way to improve the efficiency of the GRI furnace, a constant goal in the HVAC field.
    • Expectation of Success: The proposed combinations involved applying conventional sensors and established control strategies to a modulating furnace system. A POSITA would have had a high expectation of success in integrating these components to achieve the well-understood benefits of improved temperature control and greater operational efficiency.

  • Additional Grounds: Petitioner asserted additional anticipation and obviousness challenges against claims 1-2, 4, 6, 10, 12, and 15-23 based primarily on Patent 4,648,551, which Petitioner argued independently disclosed a fully modulated gas furnace that controlled fuel, circulating air, and combustion air flow in a manner that met the claim limitations.

4. Key Claim Construction Positions

  • Petitioner argued for construing several means-plus-function limitations based on corresponding structures in the ’642 patent’s specification, aligning with interpretations from the prior reexamination proceeding. Key proposed constructions included:
    • means for modulating the flow of fluid fuel: a modulating gas valve controlled by an electric signal, such as a pulse-width modulated signal.
    • means for circulating the heat transfer medium: a circulating air blower.
    • means for modulating the operation of the [circulating] means: an electrically commutated motor (ECM) capable of varying the blower speed.
    • control means: a microprocessor-based controller that receives inputs and controls the modulating gas valve, the circulating air blower motor, and the combustion air blower.

5. Relief Requested

  • Petitioner requested institution of an inter partes review and cancellation of claims 1-4, 6-7, 9-12, and 14-23 of the ’642 patent as unpatentable under 35 U.S.C. §§ 102 and/or 103.