DCT
1:18-cv-00422
Thrush Co Inc v. Wessels Co
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Thrush Co., Inc. (Indiana)
- Defendant: Wessels Company (Michigan)
- Plaintiff’s Counsel: Barrett McNagny LLP
- Case Identification: 1:18-cv-00422, S.D. Ind., 02/13/2018
- Venue Allegations: Venue is asserted based on Defendant Wessels Company having its headquarters and principal place of business in Greenwood, Indiana, within the Southern District of Indiana.
- Core Dispute: Plaintiff alleges that Defendant’s "Wess-Vent" line of air and dirt separators infringes a patent related to mechanical apparatuses for removing air and debris from liquid flows.
- Technical Context: The technology concerns fluid-handling systems, such as large-scale HVAC, where removing entrained air and particulate matter is critical for efficiency and equipment longevity.
- Key Procedural History: The complaint alleges a prior business relationship where Defendant manufactured Plaintiff's "Aar-O-Vent" product. It also alleges that Defendant purchased Plaintiff's products for reverse-engineering purposes and was sent a letter on November 2, 2016, expressly advising it of the patent-in-suit.
Case Timeline
| Date | Event |
|---|---|
| 2004-01-21 | '975 Patent Priority Date (Application Filing) |
| 2012-05-15 | U.S. Patent No. 8,177,975 Issued |
| 2016-11-02 | Plaintiff sent notice letter to Defendant |
| 2018-02-13 | Complaint Filed |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 8,177,975 - "Apparatus for Removing Air and/or Debris from a Flow of Liquid"
- Patent Identification: U.S. Patent No. 8,177,975, "Apparatus for Removing Air and/or Debris from a Flow of Liquid," issued May 15, 2012.
The Invention Explained
- Problem Addressed: The patent describes prior art air and debris separators, which often used soldered copper components, as being "difficult to manufacture," "labor intensive, time consuming, and costly," as well as not "extremely durable." (’975 Patent, col. 1:29-42).
- The Patented Solution: The invention proposes an apparatus containing a plurality of tubes, which can be formed by rolling inexpensive and durable stainless steel wire mesh, arranged parallel to each other inside a main shell. (’975 Patent, col. 2:51-56). As fluid passes through the shell, it flows across these tubes; the large surface area of the tubes causes entrained air bubbles to coalesce and rise for venting, while dirt particles impinge on the tubes and fall for collection. (’975 Patent, col. 3:48-62).
- Technical Importance: This approach sought to provide a coalescing medium that could be "easily and inexpensively manufactured" and formed of "highly durable stainless steel" to avoid the costs and durability issues of prior copper-based designs. (’975 Patent, col. 2:57-61).
Key Claims at a Glance
- The complaint asserts independent claim 13.
- The essential elements of independent claim 13 include:
- A shell with an inlet, an outlet, an inner cavity, and a "direct flow path space" between the inlet and outlet.
- A plurality of tubes oriented substantially parallel to each other inside the cavity, with their upper ends positioned above the inlet.
- At least one tube having a surface with a "plurality of apertures."
- A specific geometric arrangement where a "minority portion" of the tubes is in the direct flow path, while a "majority portion" is outside of it.
- The fluid flow between the inlet and outlet moves across this minority portion in a "substantially radial direction."
- An air vent to release the removed air.
- The complaint also alleges infringement under the doctrine of equivalents. (Compl. ¶30).
III. The Accused Instrumentality
Product Identification
- The accused products are Defendant's air and dirt separators, denominated as the "Wess-Vent." (Compl. ¶15).
Functionality and Market Context
- The complaint alleges the Wess-Vent is an air and dirt separator for use in "high-volume water heating and cooling systems." (Compl. ¶11). The functionality is described as using "stainless steel coalescing media" to break fluid surface tension, forcing air out of solution where it can be removed by an air vent. (Compl. ¶19, p. 7). The complaint includes a photograph of the accused product's coalescing element, which is a bundle of perforated tubes. (Compl. ¶19, p. 4). This image depicts a bundle of parallel, cylindrical mesh tubes designed to be placed inside the separator housing. The complaint also provides a diagram from Defendant's promotional literature, which notes the product's tank diameter is designed to reduce fluid velocity and trigger the removal of air and dirt. (Compl. ¶19, p. 7).
IV. Analysis of Infringement Allegations
'975 Patent Infringement Allegations
| Claim Element (from Independent Claim 13) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| a shell having an inlet, an outlet, and an inner cavity in fluid communication with each of the inlet and the outlet, | The Infringing Separator has a shell with an inlet and an outlet disposed as radial “arms” and in fluid connection with an inner cavity. | ¶19 | col. 3:28-34 |
| the inner cavity having a direct flow path space positioned directly between the inlet and outlet, and | The inlet and outlet are aligned, creating a straight line “direct” flow path from the inlet to the outlet. | ¶19 | col. 8:62-64 |
| a plurality of tubes positioned within the inner cavity of the shell such that the tubes are oriented substantially parallel to each other and upper ends of the tubes being positioned above the inlet, | The coalescing elements comprise a plurality of tubes oriented parallel to each other. The upper ends of the tubes are positioned above the location of the inlet. | ¶19 | col. 4:4-8 |
| each of the tubes having a longitudinal axis, and at least one of the tubes having a surface with a plurality of apertures, | Each tube has a longitudinal axis and at least one of the tubes has a plurality of apertures. A close-up photograph depicts one of the tubes as a perforated cylinder. (Compl. ¶19, p. 5). | ¶19 | col. 4:27-36 |
| a minority portion of the plurality of tubes being positioned in the direct flow path space... | The direct flow path space intersects only a minority portion of the surface of the tubes. | ¶19 | col. 9:2-4 |
| with the flow of fluid between the inlet and outlet flowing directly across the minority portion of the plurality of tubes in a substantially radial direction, | The anticipated flow path will result in fluid between the inlet and outlet flowing directly across the minority portion of the tubes to flow in a substantially radial direction. | ¶19 | col. 9:4-7 |
| a majority portion of the plurality of tubes being larger than the minority portion of the plurality of tubes and positioned outside of the direct flow path space; and | A majority portion of the tubes positioned outside the direct flow path space are larger than minority portion of the tubes within the direct flow path space. | ¶19 | col. 9:7-10 |
| an air vent positioned to release air that is removed from the flow of liquid by the plurality of tubes. | There is an air vent positioned to release air that is removed from the flow of liquid. A diagram allegedly copied from Plaintiff's literature shows a component labeled "AIR VENT." (Compl. ¶19, p. 7). | ¶19 | col. 3:34-35 |
Identified Points of Contention
- Scope Questions: The infringement analysis may focus on the construction of the geometric and quantitative limitations in claim 13. A central question will be how to define and measure the "direct flow path space," the "minority portion," and the "majority portion" of the tubes. The defense may argue that the accused product's internal geometry does not create the specific minority/majority partition required by the claim.
- Technical Questions: A factual question may arise over whether the fluid flow in the accused device is "substantially radial." The complaint asserts this is the "anticipated flow path," but the actual fluid dynamics within the device would be subject to evidentiary proof and expert testimony.
V. Key Claim Terms for Construction
The Term: "direct flow path space"
- Context and Importance: This term is foundational to the subsequent "minority portion" and "majority portion" limitations. Its size and shape—whether it is a simple line-of-sight path or a volumetric region—will dictate how many tubes fall inside or outside of it, making its definition critical to infringement.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The patent does not explicitly define the term, which could support an argument for applying its plain and ordinary meaning, potentially encompassing a wider cylindrical volume between the inlet and outlet.
- Evidence for a Narrower Interpretation: The claim requires this space to be "positioned directly between the inlet and outlet," which could be argued to limit the space to the narrowest cross-section aligned with the inlet and outlet openings, as depicted in the complaint's allegation. (Compl. ¶19, p. 4).
The Term: "minority portion" / "majority portion"
- Context and Importance: These terms quantify the claimed invention, creating a specific ratio of tubes inside versus outside the direct flow path. Practitioners may focus on these terms because infringement hinges on a quantitative, factual assessment of the accused device's internal layout.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The patent does not specify how the "portion" should be measured (e.g., by tube count, surface area, volume), potentially allowing for any reasonable method that shows the required ratio is met.
- Evidence for a Narrower Interpretation: A defendant could argue the portions must be measured by a specific metric (e.g., tube count) and that the term requires a significant and non-trivial difference between the majority and minority portions, not just a bare 51/49 split. The patent figures, such as Figure 7, show a distinct arrangement with one central assembly and six surrounding it, which could be argued to embody the claimed ratio. (’975 Patent, Fig. 7).
VI. Other Allegations
- Indirect Infringement: Count II of the complaint alleges indirect infringement, though its heading incorrectly references U.S. Patent No. 6,964,727. The substance of the count, however, pertains exclusively to the '975 patent. The complaint alleges inducement by asserting that Defendant sells the accused separators without the claimed "air vent" and provides instructions, promotional materials, and manuals that direct or suggest customers attach one. (Compl. ¶¶40, 46). The complaint also alleges contributory infringement by pleading that the separator without an air vent is not a staple article of commerce and has no substantial non-infringing use. (Compl. ¶¶38, 41).
- Willful Infringement: The complaint alleges willful infringement based on several specific factual assertions: Defendant was a former manufacturer of Plaintiff's patented product (Compl. ¶23); Defendant purchased Plaintiff's product to "reverse-engineer" it (Compl. ¶25); and Plaintiff provided Defendant with actual notice of the '975 patent via a letter dated November 2, 2016, well before the suit was filed (Compl. ¶26). The complaint further alleges that a diagram in Defendant's literature was "copied" from Plaintiff's own materials. (Compl. ¶19, p. 7).
VII. Analyst’s Conclusion: Key Questions for the Case
- A core issue will be one of claim construction and geometric application: can the phrase "direct flow path space" be defined with sufficient precision, and does the accused Wess-Vent's internal tube arrangement satisfy the specific "minority portion" and "majority portion" limitations as recited in claim 13?
- A key evidentiary question will be one of intent and history: what evidence supports the allegations of a prior manufacturing relationship, reverse-engineering, and copying? The resolution of these facts will be central to the claim for willful infringement and potential enhanced damages.
- A third question concerns indirect infringement: does Defendant's sale of separators without an air vent, coupled with its instructional materials, constitute active inducement for its customers to complete the infringing combination as claimed in the '975 patent?