Diesel Tech LLC v. Aktiebolaget Volvo

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Diesel Technologies LLC (Delaware)
  • Defendant: Aktiebolaget Volvo, dba AB Volvo (Sweden) and Volvo Group North America, LLC (Delaware)
  • Plaintiff’s Counsel: Devlin Law Firm LLC
• Case Identification: 1:22-cv-01509, N.D. Ill., 03/23/2022
• Venue Allegations: Venue is alleged against foreign defendant AB Volvo based on its introduction of products into the stream of commerce in the United States. Venue is alleged against Volvo Group North America based on a "regular and established place of business" in the district, specifically a parts distribution center in Joliet, Illinois.
• Core Dispute: Plaintiff alleges that Defendants’ exhaust aftertreatment systems, used in commercial vehicles, infringe a patent related to a method for chemically reducing non-combustible ash buildup in diesel particulate filters.
• Technical Context: The technology addresses the finite lifespan of diesel particulate filters (DPFs), a critical emissions control component, which become clogged over time with incombustible ash from engine oil and fuel additives.
• Key Procedural History: The complaint does not mention any prior litigation, IPR proceedings, or licensing history related to the patent-in-suit.

Case Timeline

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 8,474,246 - "METHOD OF OPERATING A PARTICLE FILTER IN THE EXHAUST SYSTEM OF A MOTOR VEHICLE'S INTERNAL COMBUSTION ENGINE"

• Patent Identification: U.S. Patent No. 8,474,246, "METHOD OF OPERATING A PARTICLE FILTER IN THE EXHAUST SYSTEM OF A MOTOR VEHICLE'S INTERNAL COMBUSTION ENGINE," issued July 2, 2013.

The Invention Explained

• Problem Addressed: Diesel particulate filters (DPFs) are effective at trapping soot, which can be periodically burned off in a high-temperature "regeneration" or "soot burn-off" procedure. However, these filters also accumulate non-combustible inorganic ash (e.g., from lubricant additives) which cannot be burned off and which progressively clogs the filter, increasing exhaust backpressure and eventually requiring costly filter replacement (’246 Patent, col. 1:30-41).
• The Patented Solution: The invention claims a method to reduce this accumulated ash in situ during vehicle operation. It involves heating the filter and supplying a "reducing agent" (such as hydrocarbons derived from the vehicle's own fuel) along with the exhaust gas. This agent is intended to react with and chemically convert the ash deposits (e.g., metal sulfates and phosphates) into volatile compounds that can then be carried out of the filter by the exhaust stream, thereby restoring the filter's capacity and extending its life (’246 Patent, Abstract; col. 2:1-4; col. 5:46-56). The patent's Figure 2 graphically illustrates how periodic soot burn-off procedures (R) only partially lower the filter's flow resistance, while the claimed ash reducing procedure (A) can dramatically lower the baseline resistance after it has become unacceptably high (’246 Patent, Fig. 2).
• Technical Importance: The described method offers a way to prolong the service interval of DPFs, a significant maintenance and operational cost factor for modern diesel engines, without requiring the filter to be physically removed for cleaning or replacement (’246 Patent, col. 1:52-57).

Key Claims at a Glance

• The complaint asserts independent claim 1 and dependent claims 2-4, 6, and 7 (Compl. ¶15).
• Independent Claim 1: The core claim recites a method of operating a particle filter, comprising the steps of:
  • The filter collects soot particles and ashes and is reconditioned by a soot-burn off procedure.
  • An "ash reducing procedure" reduces the mass of the ash deposits.
  • This procedure involves heating the filter and supplying a "reducing agent" with the exhaust gas.
  • The reducing agent "reacts with the ash deposits so as to chemically convert" them.
  • This conversion allows "at least non-metallic constituent parts of the ash deposits" to be carried out of the filter by the exhaust gas.
• The complaint does not explicitly reserve the right to assert other claims, but notes that Plaintiff may modify its infringement theories as discovery progresses (Compl. ¶34).

III. The Accused Instrumentality

Product Identification

• The "Accused Instrumentalities" are identified as "Volvo's exhaust aftertreatment systems (EATS) incorporating diesel particulate filters (DPF)" (Compl. ¶5, 15).

Functionality and Market Context

• The complaint alleges that these systems are used in Defendants' motor vehicles to filter soot and other particles from diesel engine exhaust (Compl. ¶5, 15). The functionality at issue is the method by which these systems manage the contents of the DPF. The complaint cites a Volvo technical manual as evidence for the existence and function of these systems (Compl. ¶5). The complaint alleges these systems are integral to Defendants' products sold in the United States, positioning them as a core component of their vehicle emission control technology (Compl. ¶5, 28).

IV. Analysis of Infringement Allegations

The complaint references an attached claim chart (Exhibit A-1) that was not filed with the public document (Compl. ¶6, 17). The infringement theory must therefore be summarized from the complaint's narrative allegations.

The plaintiff alleges that the accused Volvo EATS systems perform a method that infringes at least claim 1 of the ’246 patent (Compl. ¶17). The complaint asserts that the accused systems operate by collecting soot and ash, and are reconditioned using a burn-off procedure (Compl. ¶16). Crucially, the complaint alleges that the accused systems also perform the claimed ash reduction method by "heating the filter and supplying to the filter along with the exhaust gas of the engine a reducing agent to chemically convert the ash such that parts of the converted ash are carried out by the exhaust gas" (Compl. ¶16).

For the dependent claims, the complaint alleges that the accused systems use the engine's fuel as the reducing agent (infringing Claim 2), add this agent upstream of the filter (infringing Claim 3), and do so via fuel injection (infringing Claim 4) (Compl. ¶18-23). The complaint further alleges that the ash reducing procedure is initiated based on monitored exhaust flow resistance (infringing Claim 6) and is performed in connection with a soot-burn-off procedure (infringing Claim 7) (Compl. ¶24-27).

No probative visual evidence provided in complaint.

• Identified Points of Contention:
  • Technical Questions: A central factual question will be whether the accused Volvo systems perform a procedure that "chemically convert[s] the ash," as distinct from a standard high-temperature "soot burn-off procedure." The patent explicitly differentiates between these two processes (’246 Patent, col. 4:21-28; col. 7:37-45). The case may turn on evidence showing whether the accused systems are merely oxidizing soot or are also capable of creating the specific reducing conditions required to decompose inorganic ash like sulfates and phosphates.
  • Scope Questions: The analysis will question what constitutes a "reducing agent" under the patent's claims. Does the simple injection of diesel fuel into the hot exhaust stream, a common practice for DPF regeneration (soot burn-off), inherently create the claimed "reducing agent" for ash conversion, or does the claim require a more specific process or chemical environment?

V. Key Claim Terms for Construction

• The Term: "reducing agent"
• Context and Importance: This term is the linchpin of the infringement case. The dispute will likely focus on whether the substance and process used in Volvo's DPF regeneration cycles qualify as supplying a "reducing agent" that "chemically convert[s] the ash," or if it is merely an oxidizer for soot. Practitioners may focus on this term because its construction will determine whether conventional DPF regeneration techniques fall within the scope of the claims.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: The specification states that "in principle, any substance may be used which can cause the desired chemical conversion," listing "gaseous reducing compounds such as hydrogen, carbon monoxide or hydrocarbons" as examples (’246 Patent, col. 2:21-25). It also explicitly mentions that "a particular fuel is used for operating the engine" or is "generated from the fuel on board" can serve this function (’246 Patent, col. 2:34-37). This language could support an argument that standard diesel fuel qualifies.
  • Evidence for a Narrower Interpretation: The specification also describes more specific methods for generating the agent, such as an "under-stoichiometric operation of the internal combustion engine," or processing fuel via "a cracking-, reforming- or gasification process" (’246 Patent, col. 2:40-42, col. 2:60-64). A defendant could argue that these more detailed embodiments suggest the term implies something more than simply injecting raw fuel, but rather fuel that has been pre-processed or supplied under specific oxygen-starved conditions to create a truly reductive chemical environment.

VI. Other Allegations

• Indirect Infringement: The complaint alleges induced infringement under 35 U.S.C. § 271(b), stating that Defendants provide "instruction materials, training, and services" that cause customers and end-users to operate the accused systems in an infringing manner (Compl. ¶30-31). It also alleges contributory infringement under § 271(c), asserting that the accused DPF filters are a material component "especially made or adapted for use in an infringement" and are not a staple article of commerce suitable for substantial non-infringing use (Compl. ¶32).
• Willful Infringement: The complaint alleges Defendants had knowledge of the ’246 patent and its infringement "at least as early as of the filing of this Complaint" (Compl. ¶29). This forms the basis for a claim of post-suit willfulness.

VII. Analyst’s Conclusion: Key Questions for the Case

The resolution of this dispute will likely depend on the answers to two central questions:

1. A core issue will be one of technical mechanism: Does the accused Volvo EATS perform a distinct "ash reducing procedure" that chemically decomposes inorganic ash, as contemplated by the patent, or does its operation consist solely of a conventional "soot burn-off procedure" that uses injected fuel as an oxidizer? Evidence distinguishing these two functions will be critical.

2. The case will also turn on a question of definitional scope: Will the term "reducing agent" be construed broadly to include any hydrocarbon fuel injected into a hot exhaust stream, or will it be limited by the patent's disclosure to agents created under specific, oxygen-deficient conditions (e.g., via under-stoichiometric combustion or reforming) necessary for the chemical reduction of ash?