Personality Gym Ab v. Shandong Aochuang Fitness Equipment Co Ltd

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Personality Gym AB (Sweden)
  • Defendant: Shandong Aochuang Fitness Equipment Co., Ltd. (China)
  • Plaintiff’s Counsel: Panitch Schwarze Belisario & Nadel LLP
• Case Identification: 2:25-cv-00458, D. Nev., 03/13/2025
• Venue Allegations: Plaintiff alleges venue is proper in the District of Nevada because Defendant offered products for sale at a trade show in Las Vegas and made at least one sale to a private investigator for delivery into the District. Plaintiff also asserts that venue is proper for a foreign defendant under 28 U.S.C. § 1391(c)(3).
• Core Dispute: Plaintiff alleges that Defendant’s adjustable dumbbells infringe three U.S. patents related to mechanisms for selecting and securing weight plates.
• Technical Context: The technology concerns adjustable dumbbells, which use a single handle to engage a variable number of weight plates, thereby replacing a full rack of fixed-weight dumbbells and holding significant appeal in the home and professional fitness markets.
• Key Procedural History: The complaint alleges a history of pre-suit notice and international enforcement actions, including a cease-and-desist letter sent to the Defendant, ongoing patent litigation in China over a counterpart patent, and a German court action where Defendant’s products were seized and a default was entered. The complaint also alleges the Plaintiff provides constructive notice through virtual patent marking on its commercial website.

Case Timeline

Date	Event
2006-XX-XX	Plaintiff's predecessor brand, FLEXBELL®, launched
2009-XX-XX	Plaintiff attends ISPO Trade Show in Europe
2020-XX-XX	FLEXBELL® brand is rebranded to NÜOBELL®
2020-05-28	Earliest Patent Priority Date for Asserted Patents
2021-XX-XX	Plaintiff first learns of Defendant AOC
2023-XX-XX	Plaintiff expands business to the United States with an online store
2023-03-14	U.S. Patent No. 11,602,661 Issued
2023-03-23	Plaintiff's representative purchases AOC dumbbells from Alibaba
2023-03-27	Plaintiff receives purchased AOC dumbbells
2023-06-07	Plaintiff sends cease and desist letter to AOC
2024-01-09	U.S. Patent No. 11,865,397 Issued
2024-04-11	AOC exhibits at FIBO Trade Fair; German police seize products
2024-09-03	U.S. Patent No. 12,076,606 Issued
2025-03-07	AOC sells product to private investigator for delivery to Nevada
2025-03-11	HFA Trade Show, where AOC is allegedly offering products, begins
2025-03-13	Complaint Filed

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

U.S. Patent No. 11,602,661 - "Adjustable Weight Lifting Device"

The Invention Explained

• Problem Addressed: The patent identifies a desire to improve how weight disks are secured to a handle in adjustable dumbbells and to permit a greater number of weight disks to be secured than in prior designs (Compl. ¶12; ’661 Patent, col. 1:20-26).
• The Patented Solution: The invention utilizes a pin housed inside the dumbbell’s tubular handle. This central pin has an external thread with at least two distinct sections, each with a different helix angle (a steeper angle and a shallower angle). As the user rotates the handle, driving knobs engaged with the thread cause the pin to move axially (in or out). The different helix angles cause the pin to travel at different speeds for the same degree of rotation, allowing for a more complex and granular selection of weight plates (’661 Patent, Abstract; col. 3:15-22).
• Technical Importance: The use of a variable-pitch thread on the central pin provides a mechanically simple method for achieving multi-stage axial travel, which in turn allows a single continuous rotation of the handle to control the engagement of different combinations of weights, enhancing the device's functionality and user experience (’661 Patent, col. 9:62-col. 10:10).

Key Claims at a Glance

• The complaint asserts infringement of at least independent Claim 1 (Compl. ¶50).
• Essential elements of independent Claim 1 include:
  • a tube;
  • a pin movably disposed inside the tube, the pin comprising an external thread; and
  • one or more driving knobs extending radially inward relative to an inner wall of the tube and engaging with the external thread,
  • wherein the external thread comprises at least one portion having a first helix angle and at least one portion having a second helix angle, the second helix angle being smaller than the first helix angle.

U.S. Patent No. 11,865,397 - "Adjustable Weight Lifting Device"

The Invention Explained

• Problem Addressed: The patent addresses the challenge of providing a simple and inexpensive visual indicator for the selected weight, particularly for devices where the handle might rotate more than 360 degrees to cycle through all weight settings (’397 Patent, col. 1:29-35).
• The Patented Solution: The invention describes a housing assembly with a stationary inner portion and a rotatable outer portion. Each portion has a "face gear" on its surface. An index ring, marked with weight indicia, is driven by a system of cogwheels that mesh with both the inner and outer face gears. This gearing arrangement translates a large rotation of the handle into a small, corresponding rotation of the index ring, allowing the full range of weight settings to be displayed within a small viewing window (’397 Patent, col. 5:3-25).
• Technical Importance: This planetary-like gear system decouples the rotation of the handle from the rotation of the indicator, solving the problem of how to display a large number of discrete states (weights) resulting from multiple turns of a control mechanism in a compact and intuitive user interface.

Key Claims at a Glance

• The complaint asserts infringement of at least independent Claim 1 (Compl. ¶58).
• Essential elements of independent Claim 1 include:
  • a tube;
  • a housing having an axially inner portion nonrotatably attached to the tube and an axially outer portion that is rotatable relative to the axially inner portion;
  • the axially inner portion comprising an axially inner portion face gear facing the axially outer portion and the axially outer portion having an axially outer portion face gear facing the axially inner portion;
  • an index ring comprising an exterior surface provided with indicia and an inner surface;
  • one or more gears or cogwheels mounted on the inner surface of the index ring for rotation and meshing with both the inner and outer portion face gears.

U.S. Patent No. 12,076,606 - "Adjustable Weight Lifting Device"

Technology Synopsis

This patent claims the fundamental assembly of the dumbbell handle. It describes a device comprising a tube, a cylindrical member inside the tube, and first and second housings. The invention specifies that the housings have inner portions nonrotatably attached to the tube and outer portions nonrotatably attached to the cylindrical member, while the tube and cylindrical member can rotate relative to each other, forming the core rotating mechanism (’606 Patent, Abstract; Claim 1).

Asserted Claims

The complaint asserts infringement of at least independent Claim 1 (Compl. ¶66).

Accused Features

The complaint alleges that the overall mechanical structure of the AOC dumbbell, which employs a rotating handle (tube) and internal components (cylindrical member) connected to housings at either end, infringes this patent (Compl. ¶¶ 17, 29).

III. The Accused Instrumentality

Product Identification

The accused products are Defendant AOC’s "round and octagonal adjustable dumbbells," which are allegedly sold in the United States via online marketplaces like Alibaba and offered for sale at industry trade shows (Compl. ¶¶ 18, 27, 42).

Functionality and Market Context

The accused products are alleged to function by allowing a user to adjust the weight by turning the handle, which adds or removes weight disks at either end (Compl. ¶19). The complaint alleges that after purchasing and dismantling an accused dumbbell, Plaintiff determined it was a "copy/knock-off" of its own NÜOBELL® product (Compl. ¶28). Specifically, the complaint alleges the AOC product incorporates the same weight adjustment system and method, including pins with dual-helix-angle threads (Compl. ¶¶ 29-30). To support the allegation of direct copying, the complaint includes a photograph of what it claims are unique molding marks on the deconstructed AOC product that are identical to those on Plaintiff's product (Compl. ¶36, p.11). This picture shows two internal plastic components, one from the accused product and one presumably from the plaintiff's, with arrows pointing to allegedly identical tooling marks (Compl. p. 11).

IV. Analysis of Infringement Allegations

U.S. Patent No. 11,602,661 Infringement Allegations

Claim Element (from Independent Claim 1)	Alleged Infringing Functionality	Complaint Citation	Patent Citation
a tube	The handle of the AOC dumbbell that a user grips and rotates to select weight.	¶19	col. 3:6-7
a pin movably disposed inside the tube, the pin comprising an external thread	The deconstructed AOC dumbbell allegedly contains internal pins with external threads that move axially to engage weights.	¶30	col. 3:8-10
one or more driving knobs extending radially inward relative to an inner wall of the tube and engaging with the external thread	The AOC product is alleged to use the same weight adjustment system, which implies the presence of knobs or equivalent structures that engage the pin's threads to drive its movement.	¶29	col. 3:33-41
wherein the external thread comprises at least one portion having a first helix angle and at least one portion having a second helix angle, the second helix angle being smaller than the first helix angle	The complaint makes the specific factual allegation that the "deconstructed AOC round adjustable dumbbell shows pins with external threads where the external threads have two helix angles."	¶30	col. 3:15-22

U.S. Patent No. 11,865,397 Infringement Allegations

Claim Element (from Independent Claim 1)	Alleged Infringing Functionality	Complaint Citation	Patent Citation
a tube	The handle of the AOC dumbbell.	¶19	col. 4:21-24
a housing having an axially inner portion nonrotatably attached to the tube...and an axially outer portion that is rotatable relative to the axially inner portion	The complaint alleges the accused product is "virtually identical" and incorporates the same "weight adjustment method," which includes the claimed housing structure for translating rotation into a weight indication.	¶34	col. 4:56-63
the axially inner portion comprising an axially inner portion face gear...and the axially outer portion having an axially outer portion face gear	As part of the allegedly copied weight adjustment system, the AOC product is asserted to contain the claimed interacting face gears that drive the weight indicator.	¶29	col. 4:50-55
an index ring comprising an exterior surface provided with indicia	A photograph of the dismantled AOC product shows a ring with numerical weight markings.	p. 10	col. 4:56-63
one or more gears or cogwheels mounted on the inner surface of the index ring...meshing with the...face gear[s]	The allegation of copying the complete "weight adjustment system" and "characteristic features" implies the presence of this gearing mechanism.	¶¶29, 34	col. 5:3-15

Identified Points of Contention

• Technical Questions: A primary question will be whether discovery and expert analysis confirm the factual allegations from Plaintiff's teardown. Does the accused product's pin in fact have an external thread with two measurably different helix angles as required by the ’661 Patent? Does its weight indication system operate using the specific dual face gear and cogwheel arrangement claimed in the ’397 Patent?
• Scope Questions: The infringement analysis for the ’397 Patent may raise the question of whether the structures in the accused device constitute "face gears" as the term is used in the patent. The analysis will depend on the evidence of how those components are shaped and how they interact.

V. Key Claim Terms for Construction

For U.S. Patent No. 11,602,661

• The Term: "second helix angle being smaller than the first helix angle"
• Context and Importance: This relative dimensional limitation is the core technical distinction of the asserted independent claim of the ’661 Patent. The infringement case hinges on whether the accused device meets this specific geometric constraint. Practitioners may focus on this term because it requires a quantitative comparison, and any dispute will likely involve competing expert measurements and functional analysis.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: The claim language does not quantify how much smaller the angle must be, suggesting any non-zero difference could meet the limitation. The specification repeatedly refers simply to a "first (larger) helix angle" and a "second (smaller) helix angle," which may support an interpretation that any discernible difference is sufficient (’661 Patent, col. 7:26-30).
  • Evidence for a Narrower Interpretation: A defendant might argue that the term implies a functionally significant difference in angle, necessary to produce the different rates of axial travel described in the specification (’661 Patent, col. 8:15-33). They could contend that minor, incidental variations from a single target angle do not meet the limitation.

For U.S. Patent No. 11,865,397

• The Term: "face gear"
• Context and Importance: This term defines the key interacting components of the weight indication mechanism in the ’397 Patent. The construction of this term is critical because it will determine whether the gear-like structures on the internal components of the accused dumbbell fall within the scope of the claims.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: The patent uses the term in the context of a "gearing arrangement" where a "cogwheel...meshes with the...face gear" to produce relative rotation (’397 Patent, col. 5:11-15). This functional description could support a broad definition covering any toothed surfaces on the face of a component that achieve this meshing function, regardless of specific tooth profile.
  • Evidence for a Narrower Interpretation: The figures depict the face gears (items 91 and 93) as having a specific sawtooth-like profile (’397 Patent, Fig. 5F). A defendant could argue these specific embodiments limit the term to the depicted structure, or at least to something more specific than any generic set of interacting teeth.

VI. Other Allegations

Indirect Infringement

The complaint alleges that AOC sells the accused products to third parties, identified as John Does 1-30, for the purpose of resale in the United States (Compl. ¶41). Further, the infringement counts accuse AOC of "causing to be made" infringing products, which is language that supports a claim for induced infringement (Compl. ¶50).

Willful Infringement

The complaint alleges that AOC's infringement is willful based on both actual and constructive knowledge of the Asserted Patents. The basis for actual knowledge includes prior correspondence (a cease-and-desist letter), the seizure of its products by German authorities in a separate patent action, and ongoing patent litigation in China over a counterpart patent (Compl. ¶¶ 31-32, 35, 52). The complaint also alleges constructive knowledge based on Plaintiff's virtual patent marking on its website (Compl. ¶¶ 38-39). The allegations of "slavish copying," supported by photographic evidence of allegedly identical molding marks, are also presented to show deliberate and willful conduct (Compl. ¶36).

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

• A central evidentiary question will be one of technical verification: will discovery and expert testimony substantiate the complaint’s core factual allegations, derived from a product teardown, that the accused dumbbell’s internal mechanism contains a pin with a dual-helix angle thread (’661 Patent) and a weight indicator driven by a dual face-gear system (’397 Patent)?
• A key issue for damages and potential enhancement will be one of intent and copying: how will the court interpret the evidence of alleged "slavish copying," including identical molding marks, in light of the defendant's alleged pre-suit knowledge from multiple international enforcement actions?
• The case may also turn on a question of claim construction and scope: can the term "face gear" be interpreted broadly enough to read on the specific structures within the accused device, and is any measurable difference in thread pitch sufficient to meet the "smaller than the first helix angle" limitation?