Diesel Tech LLC v. Caterpillar Inc

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Diesel Technologies LLC (Delaware)
  • Defendant: Caterpillar, Inc. (Delaware)
  • Plaintiff’s Counsel: DEVLIN LAW FIRM LLC
• Case Identification: 3:25-cv-50026, N.D. Ill., 01/17/2025
• Venue Allegations: Venue is alleged based on Defendant’s established places of business in the district, including corporate offices and technical centers, as well as its regular transaction of business and sale of accused products within the district.
• Core Dispute: Plaintiff alleges that Defendant’s diesel engines equipped with Exhaust After-Treatment Systems infringe a patent related to a method for regenerating diesel particulate filters by chemically reducing accumulated ash.
• Technical Context: The technology addresses the challenge of extending the operational life of diesel particulate filters (DPFs), a critical component for meeting modern emissions standards in commercial and industrial vehicles.
• Key Procedural History: The complaint does not mention any prior litigation, inter partes review (IPR) proceedings, or licensing history related to the patent-in-suit. The claim of willfulness is based on notice provided by the filing of the instant complaint.

Case Timeline

Date	Event
2003-12-18	Priority Date for U.S. Patent No. 8,474,246
2013-07-02	Issue Date for U.S. Patent No. 8,474,246
2025-01-17	Complaint Filed

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"

The Invention Explained

• Problem Addressed: Diesel Particulate Filters (DPFs) are effective at trapping soot, which can be periodically burned off in a "regeneration" cycle. However, they also accumulate non-combustible inorganic ash from engine oil and fuel additives. This ash buildup gradually clogs the filter, increasing backpressure on the engine and ultimately requiring costly filter replacement or off-line servicing (’246 Patent, col. 1:30-41).
• The Patented Solution: The invention describes a method to reduce this ash buildup during the vehicle's normal operation. The method involves heating the DPF and introducing a "reducing agent" with the exhaust gas. This agent is designed to chemically react with the non-metallic components of the ash (e.g., sulfates, phosphates), converting them into volatile compounds that can then be expelled from the filter with the exhaust stream (’246 Patent, Abstract; col. 1:60-2:8). This process is distinct from a standard soot burn-off, which is an oxidation process.
• Technical Importance: By enabling the removal of performance-degrading ash, the invention claims to extend the DPF’s useful life, reduce maintenance costs, and help vehicles maintain compliance with stringent emissions standards over longer periods (Compl. ¶13, ¶18).

Key Claims at a Glance

• The complaint asserts independent claim 1 and dependent claims 2, 3, 4, and 7 (Compl. ¶28).
• Independent Claim 1 requires the essential elements of:
  • A method of operating a particle filter in a motor vehicle engine exhaust system, where the filter collects both soot and ash and is periodically reconditioned by a soot-burn off procedure.
  • The method comprises an "ash reducing procedure" that reduces the mass of the ash deposits.
  • This reduction is achieved by heating the filter and supplying a "reducing agent" with the exhaust gas.
  • The reducing agent chemically converts the ash deposits so that "at least non-metallic constituent parts of the ash deposits are carried out of the particle filter."

III. The Accused Instrumentality

Product Identification

The complaint identifies the "Accused Instrumentalities" as Caterpillar engines equipped with an Exhaust After-Treatment System (EATS) that includes a Diesel Particulate Filter (DPF) (Compl. ¶28). Specific engine models named are the Caterpillar C9.3 ACERT Tier 4 Engine, with the C13, C15, and C18 ACERT Tier 4 engines also identified as containing the same allegedly infringing functionality (Compl. ¶28).

Functionality and Market Context

The complaint alleges these EATS-equipped engines are used to comply with modern emissions standards by filtering particulate matter from the exhaust (Compl. ¶26). The core accused functionality is the engine's DPF regeneration process, which Plaintiff alleges performs not only a standard soot burn-off but also the patented ash-reduction method (Compl. ¶29). The complaint asserts that the patented method provides significant commercial value and cost advantages, implying the accused products are commercially significant (Compl. ¶18).

IV. Analysis of Infringement Allegations

The complaint references an infringement claim chart in an "Exhibit B" that was not provided with the filed complaint (Compl. ¶30, ¶32, ¶34, ¶36, ¶38). The infringement theory, based on the narrative allegations in the complaint, is as follows:

The complaint alleges that the Accused Instrumentalities directly infringe claim 1 by performing a method of operating a DPF that collects soot and ash (Compl. ¶29). It alleges that the engines' regeneration cycle constitutes an "ash reducing procedure" by heating the filter and supplying a "reducing agent" (engine fuel) that chemically converts ash, allowing parts of it to be carried out by the exhaust (Compl. ¶29, ¶31). The allegations for the dependent claims specify that this reducing agent is the engine's fuel (Claim 2), is added upstream of the DPF (Claim 3) via fuel injection (Claim 4), and that the ash reduction is performed in connection with the soot-burn-off procedure (Claim 7) (Compl. ¶31-38).

No probative visual evidence provided in complaint.

V. Key Claim Terms for Construction

"reducing agent"

Context and Importance: This term is central to the invention. The outcome of the case may depend on whether the diesel fuel used in the accused Caterpillar systems for soot regeneration qualifies as a "reducing agent" for ash under the patent's definition. Practitioners may focus on this term because infringement hinges on showing the accused system does more than just oxidize soot.

Intrinsic Evidence for Interpretation:

• Evidence for a Broader Interpretation: The specification suggests the agent can be derived directly from the vehicle's fuel, stating "a particular fuel is used for operating the engine is employed or the reducing agent is produced from the fuel on board of the motor vehicle" (’246 Patent, col. 7:26-29; Claim 2).
• Evidence for a Narrower Interpretation: The specification describes creating specific "reactive compounds" through processes like "cracking-, reforming- or gasification" designed to chemically convert "phosphates and sulfates" (’246 Patent, col. 2:41-46, col. 5:41-44). A defendant could argue this implies that a "reducing agent" is not simply raw fuel, but fuel that has been processed to create specific chemical species for reacting with ash.

"ash reducing procedure"

Context and Importance: This phrase distinguishes the claimed invention from a conventional "soot-burn-off procedure." Plaintiff must prove that the accused systems perform this specific, additional procedure. The distinction is critical because DPFs are widely understood to perform soot burn-offs, but not necessarily ash reduction.

Intrinsic Evidence for Interpretation:

• Evidence for a Broader Interpretation: Claim 7 recites performing the ash reducing procedure "in connection with a soot-burn-off procedure," which could suggest they can be part of a single, integrated operational cycle (’246 Patent, col. 8:46-49).
• Evidence for a Narrower Interpretation: The patent's background distinguishes ash accumulation as a separate problem from soot accumulation (’246 Patent, col. 1:30-41). Furthermore, Figure 2 depicts the "soot particle burn-off procedures R" and the "ash deposit reducing procedure A" as distinct events with different effects on the filter's backpressure, suggesting they are conceptually and functionally separate, even if performed sequentially (’246 Patent, Fig. 2; col. 5:26-28).

VI. Other Allegations

Indirect Infringement

The complaint alleges induced infringement under 35 U.S.C. § 271(b). The factual basis alleged is that Caterpillar provides "instruction materials, training, and services" that instruct and encourage end users to operate the Accused Instrumentalities in a manner that directly infringes the ’246 Patent (Compl. ¶41-42).

Willful Infringement

Willfulness is alleged based on post-suit knowledge only. The complaint asserts that Caterpillar was made aware of the patent and its alleged infringement "at least as early as the filing of this Complaint" and that any subsequent infringement is therefore willful (Compl. ¶40, ¶43). No facts supporting pre-suit knowledge are alleged.

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

• A central issue will be one of functional distinction: Does the accused Caterpillar DPF regeneration process, which is primarily understood to oxidize soot, also perform the specific chemical conversion of non-metallic ash components (e.g., sulfates, phosphates) into volatile compounds as required by Claim 1? The case may require detailed expert testimony and evidence to distinguish between the well-known phenomenon of soot burn-off and the claimed ash reduction mechanism.
• The dispute will likely also involve a question of definitional scope: Can the term "reducing agent", as described in a patent that details the creation of specific reactive species for ash conversion, be construed to cover diesel fuel injected for the primary purpose of soot combustion, or does the term require a more specific chemical function and intent?