DCT
1:26-cv-10573
Ningbo Haoyang Jixie Gongju Youxian Gongsi v. Zhong
Key Events
Complaint
Table of Contents
complaint Intelligence
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Ningbo Haoyang Jixie Gongju Youxian Gongsi (China)
- Defendant: Duoming Zhong (China)
- Plaintiff's Counsel: BOYLE FREDRICKSON, S.C.
- Case Identification: 1:26-cv-10573, N.D. Ill., 09/01/2026
- Venue Allegations: Plaintiff asserts that venue is proper because the Defendant, a non-U.S. resident, may be sued in any judicial district. Further, it is alleged that the Defendant acknowledged the appropriateness of the venue by previously filing a related patent infringement suit in the same district.
- Core Dispute: Plaintiff seeks a declaratory judgment that Defendant's patent related to adjustable weight dumbbells is invalid and/or unenforceable.
- Technical Context: The technology concerns mechanical systems for quickly and securely adjusting the weight of a dumbbell by adding or removing counterweight blocks.
- Key Procedural History: This declaratory judgment action follows a patent infringement suit filed by the patent owner, Duoming Zhong, against the plaintiff, NHJYG, on June 24, 2026 (Case No. 1:26-cv-07374). That case was voluntarily dismissed without prejudice two days later. The plaintiff alleges that this history creates a reasonable apprehension of a future infringement suit, establishing the basis for the current action.
Case Timeline
| Date | Event |
|---|---|
| 2023-07-08 | '453 Patent Priority Date |
| 2026-04-07 | '453 Patent Issue Date |
| 2026-06-24 | Prior infringement suit filed by Zhong against NHJYG |
| 2026-06-26 | Prior infringement suit voluntarily dismissed without prejudice |
| 2026-09-01 | Complaint for Declaratory Judgment of Invalidity filed |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 12,594,453 - "WEIGHT-ADJUSTABLE DUMBBELL"
- Patent Identification: U.S. Patent No. 12,594,453, titled "WEIGHT-ADJUSTABLE DUMBBELL," issued on April 7, 2026.
The Invention Explained
- Problem Addressed: The patent's background section identifies that conventional dumbbells requiring the user to screw and unscrew fixing nuts to adjust weight are "complicated in operation and wastes time and labor" '453 Patent, col. 1:27-32
- The Patented Solution: The invention discloses a dumbbell with a quick-connect mechanism for adding or removing auxiliary weight blocks. The system uses a "first spinning buckle" on an auxiliary block that inserts into a "first spinning slot" on a main block '453 Patent, Claim 1 The user inserts the block via a "notch" in the slot and then rotates it, causing a "first stop convex block" on the buckle to engage a "first stop edge" inside the slot, thereby locking the weights together '453 Patent, col. 5:6-25 This allows for rapid assembly and disassembly without threaded nuts.
- Technical Importance: This approach aims to streamline workouts by enabling faster weight changes than traditional screw-collar dumbbells, a valuable feature in fitness routines that involve frequent adjustments. '453 Patent, col. 5:5-9
Key Claims at a Glance
- The complaint seeks a declaration that all claims of the '453 patent are invalid Compl. ¶15 Compl., Request for Relief A Independent claim 1 is the broadest claim.
- The essential elements of Independent Claim 1 include:
- A handle.
- Counterweight block groups with main and auxiliary blocks.
- A "first connecting part" on the auxiliary block, defined as a "first spinning buckle" with a "first stop convex block."
- A "first connecting fitting part" on the main block, defined as a "first spinning slot" with a "first stop edge" and a "first notch."
- A connection method wherein the buckle is inserted into the slot via the notch and then rotated, causing the stop edge to stop the convex block, combining the blocks "to form a whole."
- The complaint does not reserve the right to assert dependent claims as this is a declaratory judgment action for invalidity of all claims.
III. The Accused Instrumentality
Product Identification
- The complaint identifies Plaintiff's "EQUIPRO dumbbells" as the product line at the center of the dispute Compl. ¶8
Functionality and Market Context
- The complaint states that NHJYG sells these adjustable weight dumbbells through online retailers like Amazon Compl. ¶1 Compl. ¶8 A product image shows a dumbbell set with multiple weight plates that can be attached to a central handle Compl. p. 2, FIG. at ¶7 The complaint does not provide a detailed technical description of the EQUIPRO dumbbells' adjustment mechanism, but the context of the dispute suggests it involves a method for attaching and detaching weight plates that the patent owner, Zhong, had previously alleged was infringing.
IV. Analysis of Invalidity Allegations
The complaint does not allege infringement but instead alleges that all claims of the '453 patent are invalid as anticipated or rendered obvious by prior art. The following table summarizes the complaint's allegations that UK Patent Application GB2610854A ("GB '854A") anticipates the invention claimed in the '453 patent.
U.S. Patent No. 12,594,453 Invalidity Allegations (per UK Pat. App. GB2610854A)
| Claim Element (from Independent Claim 1) | Alleged Prior Art Disclosure (per Complaint) | Complaint Citation | Patent Citation |
|---|---|---|---|
| a handle; and counterweight block groups, wherein the counterweight block groups comprise main counterweight blocks and auxiliary counterweight blocks | The complaint alleges GB '854A discloses a modular free weight system with a handle, main counterweight blocks, and auxiliary counterweight blocks. | ¶16 | col. 10:31-38 |
| wherein each first connecting part is a first buckle part; each first connecting fitting part is a first buckle fitting part | The complaint alleges GB '854A discloses that the main and auxiliary blocks have detachably connectable connecting parts. | ¶16 | col. 10:44-51 |
| wherein the first buckle part is a first spinning buckle...the first buckle fitting part is a first spinning slot | The complaint alleges these connecting parts comprise "(spinning) buckles / boss(es) and buckle fitting parts." | ¶16 | col. 10:52-54 |
| the first spinning buckle is provided with a first stop convex block; the first spinning slot is provided with a first stop edge; the first stop edge is provided with a first notch | The complaint alleges the spinning buckles have "first stop convex block(s)" and the spinning slots have "first stop edge(s) with notch(es)." | ¶16 | col. 10:54-58 |
| wherein the first spinning buckle is rotated... so that the main counterweight block and the auxiliary counterweight block are combined to form a whole | The complaint alleges the spinning buckle can be inserted into the slot and rotated so the blocks are "combined to form whole(s)." A figure from the cited prior art is provided as an example. Compl. p. 4, FIG. 1C | ¶16 | col. 11:1-4 |
- Identified Points of Contention:
- Scope Questions: The dispute will likely center on whether the terminology used in the complaint to describe the prior art (e.g., "spinning buckles") accurately reflects structures that meet the specific limitations of the claims in the '453 patent. The patent owner may argue for a narrower construction of the claim terms that distinguishes them from the prior art disclosures.
- Technical Questions: A key question for the court will be whether the connection mechanisms shown in the prior art figures, such as the exploded view from UK Pat. App. GB2610854A Compl. p. 4, FIG. 2A, function in a manner identical to the claimed invention. The complaint also raises invalidity under 35 U.S.C. § 112, suggesting that the clarity and sufficiency of the patent's own disclosure will be at issue Compl. ¶20
V. Key Claim Terms for Construction
The Term: "first spinning buckle" / "first spinning slot"
- Context and Importance: These terms define the core interlocking mechanism of the invention. The validity of the patent hinges on whether this specific mechanism was already disclosed in the prior art. Practitioners may focus on this term because the complaint explicitly alleges that prior art discloses "(spinning) buckles" and "spinning slot(s)" Compl. ¶16, creating a direct challenge to the novelty of this claimed element.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The patent describes the structure in general terms as a "first buckle part" and a "first buckle fitting part" that are "detachably connected" '453 Patent, col. 1:49-52, which could suggest a wider range of rotating connection types.
- Evidence for a Narrower Interpretation: Claim 1 itself recites specific structural features: the buckle must have a "first stop convex block" and the slot must have a "first stop edge" and a "first notch" '453 Patent, Claim 1 The patent owner would likely argue these limitations narrow the term to a specific configuration not identically present in any single prior art reference.
The Term: "locking device"
- Context and Importance: This term appears in dependent claim 2 and is central to the validity of claims that add a secondary locking feature. The complaint alleges that the prior art discloses a "locking device that locks the main and auxiliary counterweight block(s)" Compl. ¶16, directly challenging the patentability of this feature.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The patent first introduces the concept generally as a device that "locks the main counterweight block to the auxiliary counterweight block" when the spinning buckle is rotated '453 Patent, col. 2:4-10
- Evidence for a Narrower Interpretation: Claim 3 further defines the locking device as comprising an "elastic locking buckle" and a "first locking slot" '453 Patent, Claim 3 The specification and figures illustrate this with specific components like a "positioning ball (4)" and "positioning spring (10)" '453 Patent, col. 9:8-14 '453 Patent, FIG. 5, which may be used to argue for a more constrained definition of the term.
VI. Other Allegations
The complaint is a declaratory judgment action for invalidity and does not contain allegations of indirect or willful infringement.
VII. Analyst's Conclusion: Key Questions for the Case
This case appears to be a preemptive validity challenge prompted by a prior, quickly-dismissed infringement suit. The resolution will likely depend on the answers to the following questions:
- A central issue will be one of claim scope versus prior art: Will the claim term "spinning buckle," with its specific "stop convex block" and "notch" features, be construed narrowly enough to distinguish it from the connecting mechanisms disclosed in the prior art references cited by NHJYG, such as UK Pat. App. GB2610854A?
- A key factual question will be one of obviousness: Even if no single prior art reference anticipates the claims, would a person of ordinary skill in the art, reviewing the multiple references cited in the complaint Compl. ¶14, have been motivated to combine their respective features to create the specific quick-connect dumbbell system claimed in the '453 patent?
- A third critical question will address patent adequacy under 35 U.S.C. § 112: Does the language of the claims, when read in light of the specification, "particularly point out and distinctly claim" the invention, or are the terms indefinite, not enabled, or lacking written description as alleged by the plaintiff Compl. ¶20?
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