Xiangshan Zhang v. Vivosun Inc

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Xiangshan Zhang (China)
  • Defendant: Vivosun INC. (California)
  • Plaintiff's Counsel: Bayramoglu Law Offices, LLC
• Case Identification: 5:26-cv-02458, C.D. Cal., 05/08/2026
• Venue Allegations: Venue is alleged in the Central District of California because the Defendant, a California corporation with a principal place of business in the district, has allegedly committed infringing acts within the district and maintains a regular and established place of business there.
• Core Dispute: Plaintiff alleges that Defendant's collapsible utility wagon infringes a patent related to a specific mechanical folding mechanism that prevents the wagon from increasing in height when collapsed.
• Technical Context: The technology concerns the mechanical design of foldable utility carts, a consumer product category where compact storage is a key feature.
• Key Procedural History: This lawsuit follows a prior case between the same parties ("Vivosun Litigation 1"), which concerned an "Original Infringing Product." The current complaint targets a "modified version" of that product. The plaintiff alleges that a motion to add this modified product to the original lawsuit was denied, necessitating the filing of this separate action. The complaint also alleges Defendant had notice of the patent and infringement as early as September 2022 through direct communication and via a report filed with Amazon.com.

Case Timeline

Date	Event
2017-01-01	Plaintiff began work on the patented product
2018-09-01	'010 Patent Priority Date
2020-04-28	'010 Patent Issue Date
2022-07-01	Plaintiff learned of Defendant's "Original Infringing Product"
2022-09-15	Plaintiff allegedly gave Defendant actual knowledge of the '010 Patent
2022-09-22	Amazon.com allegedly notified Defendant of an infringement report
2023-01-01	Plaintiff learned of the "Accused Product" (modified version)
2023-11-11	Plaintiff filed "Vivosun Litigation 1" against Defendant
2024-05-01	Plaintiff informed Defendant that the Accused Product infringes the '010 Patent
2026-05-08	Complaint Filing Date

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

U.S. Patent No. 10,633,010 - "TRAILER WITH NO EXTRA HEIGHT WHEN FOLDING"

• Identification: U.S. Patent No. 10,633,010, issued April 28, 2020 (the "'010 Patent").

The Invention Explained

• Problem Addressed: The patent's background section identifies shortcomings in prior art foldable trailers, noting that they often have small capacity and, critically, that their "heights and volume are increased after folding" '010 Patent, col. 1:18-20 This makes them less convenient to store than desired.
• The Patented Solution: The invention claims to solve this problem through a specific mechanical structure. It describes a trailer built around fixed vertical "standpipes" with a series of interconnected "front and rear folding components," "side folding components," and "bottom folding components" '010 Patent, abstract This arrangement of cross-pipes, sliding sleeves, and driving pipes is designed to allow the trailer to collapse inward without its overall height changing, thus achieving a smaller folded volume than prior designs '010 Patent, col. 2:61-col. 3:2
• Technical Importance: The design aims to provide a more practical and convenient folding cart by maximizing space savings when the cart is not in use '010 Patent, abstract

Key Claims at a Glance

• The complaint asserts independent Claim 1 Compl. ¶40 Compl. ¶43
• The essential elements of independent Claim 1 include:
  • A trailer with no extra height when folding.
  • Comprising fixed standpipes, front/rear folding components, side folding components, bottom folding components, and handle components.
  • A "top-corner fixed piece" fixed on the standpipes and slidably connected with a "first linkage sliding sleeve".
  • The front/rear folding components comprise hinged "X components" formed by cross pipes, which are hinged to the top-corner fixed piece or the first linkage sliding sleeve.
  • The side folding components comprise two "side folding shelves" and a "folding driving pipe," with a detailed arrangement of side cross short pipes, side cross long pipes, and horizontal connecting pipes.
  • The bottom folding components comprise two "bottom X components" formed by bottom connecting pipes hinged to a "second linkage sliding sleeve" or a "bottom-corner fixed piece".
• The complaint explicitly pleads infringement of claims 1-8 and 10 and reserves the right to assert other claims Compl. ¶41 Compl. ¶42

III. The Accused Instrumentality

Product Identification

• The accused instrumentality is the "Vivosun Collapsible Folding Wagon Outdoor Utility" (the "Accused Product") Compl. ¶27

Functionality and Market Context

• The complaint identifies the Accused Product as a collapsible wagon sold by Defendant Vivosun on its own website and on Amazon.com Compl. ¶20 It is described as a "modified version" of a product that was the subject of a prior lawsuit between the parties Compl. ¶25 The complaint alleges that the Accused Product competes directly with products sold by the Plaintiff's U.S. licensees, reducing their market share and impairing their sales rankings Compl. ¶31 Compl. ¶33 The complaint states that pictures of the accused wagon are provided in an exhibit. A representative image shows a collapsible utility wagon with a visible crisscrossing frame structure, consistent with the general type of product described in the patent Compl. ¶2 Compl. Ex. 2

IV. Analysis of Infringement Allegations

The complaint alleges that the Accused Product contains every element of Claim 1 of the '010 Patent Compl. ¶43 The allegations are summarized in the table below, which is based on the claim language block-quoted in the complaint.

'010 Patent Infringement Allegations

Claim Element (from Independent Claim 1)	Alleged Infringing Functionality	Complaint Citation	Patent Citation
A trailer with no extra height when folding, comprising fixed standpipes arranged at a front and rear end of the trailer, and front and rear folding components, side folding components, bottom folding components and handle components connected to the fixed standpipes;	The complaint alleges the Accused Product is a collapsible trailer with a folding frame structure connected to fixed standpipes.	¶43	col. 3:65-col. 4:3
wherein a top-corner fixed piece is fixed on the fixed standpipes, and slidably connected with a first linkage sliding sleeve;	The Accused Product is alleged to have fixed pieces at the top corners of its frame and a sliding sleeve mechanism on the standpipes.	¶43	col. 4:9-15
the front and rear folding components comprise at least two hinged front and rear X components, the front and rear X components are formed by two cross pipes which are crosswise hinged together by an articulated shaft, the ends of the cross pipes are hinged with the top-corner fixed piece or the first linkage sliding sleeve;	The Accused Product is alleged to possess front and rear "X"-shaped folding structures made of cross-hinged pipes.	¶43	col. 4:24-32
wherein the side folding components comprise two side folding shelves and a folding driving pipe, the side folding shelf comprises a side cross short pipe, a side cross long pipe and a horizontal connecting pipe, the side cross short pipe and the side cross long pipe are crosswise hinged by articulated shaft;	The Accused Product is alleged to incorporate the specific combination of shelves, driving pipes, short pipes, and long pipes that form the side folding structure.	¶43	col. 4:33-39
one end of the folding driving pipes is hinged with two said horizontal connecting pipes, and the other end thereof is hinged with ends of two said side cross long pipes; the other end of the side cross long pipe is hinged with the top-corner fixed piece, one end of the side cross short pipe is hinged with the first linkage sliding sleeve and the other end thereof is hinged with one end of the horizontal connecting pipe;	The Accused Product is alleged to have the specific and detailed set of hinge connections between the various pipes and sleeves of the side folding components as recited in the claim.	¶43	col. 4:39-52
the bottom folding components comprise two bottom X components, the bottom X components are formed by one end of four bottom connecting pipes being simultaneously hinged with one same bottom connecting piece; the other end of the bottom connecting pipe is hinged with a second linkage sliding sleeve slidably connected with the folding driving pipe or a bottom-corner fixed piece fixedly connected to the fixed standpipes.	The Accused Product is alleged to have a bottom folding mechanism with "X"-shaped components and a second sliding sleeve connected as described in the claim.	¶43	col. 4:53-61

Identified Points of Contention

• Scope Questions: Claim 1 is highly detailed and recites a precise combination of structural elements (e.g., "side cross short pipe," "first linkage sliding sleeve," "second linkage sliding sleeve"). The central dispute will likely involve a meticulous, element-by-element comparison. A potential question is: Does the accused "modified" product Compl. ¶25 omit, combine, or alter any of the specific structural components recited in Claim 1, thereby creating a potential non-infringement argument?
• Technical Questions: The complaint alleges the Accused Product is a "modified design" from a product in prior litigation Compl. ¶¶25-29 A key factual question for the court will be to determine the nature of these modifications and whether they are material to the infringement analysis. What evidence does the complaint provide that the accused wagon's folding action is achieved by the specific interplay of a "folding driving pipe" and a "second linkage sliding sleeve" as required by the claim, rather than a different mechanical arrangement?

V. Key Claim Terms for Construction

• The Term: "with no extra height when folding"
• Context and Importance: This phrase appears in the patent title, the summary, and the preamble of Claim 1. Its construction is critical because it describes the core functional advantage of the invention. Practitioners may focus on this term because Defendant could argue it is a strict functional limitation that its product, if its height changes even nominally, does not meet. Plaintiff may argue it sets the context for the structural limitations that achieve this result.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: A party arguing for a broader or contextual reading might point out that the body of the claim is entirely structural. They may argue the preamble simply states the intended purpose of the detailed structural arrangement that follows, and infringement hinges on the presence of those structures, not a perfect zero-change in height.
  • Evidence for a Narrower Interpretation: A party arguing for a narrower, more limiting interpretation would cite the patent's repeated emphasis on this feature. The specification states, "the height of the trailer does not change after folding" '010 Patent, col. 2:64-65 and "the side height and the front and rear height of the trailer are unchanged after folding" '010 Patent, claim 10 This language may support an argument that "no extra height" is a hard requirement for infringement, not merely a goal.

VI. Other Allegations

• Indirect Infringement: The complaint makes a general allegation of induced infringement Compl. ¶40, asserting that Vivosun's actions cause others to infringe. However, it does not specify the particular acts, such as providing user manuals or advertising that instructs on an infringing use, that form the basis of this allegation.
• Willful Infringement: The complaint alleges a basis for willfulness by asserting Defendant had knowledge of the '010 Patent and its alleged infringement. The alleged knowledge stems from direct communications on or about September 15, 2022 Compl. ¶22, a notice from Amazon.com on September 22, 2022 Compl. ¶23, and the proceedings in the prior "Vivosun Litigation 1" Compl. ¶24 Compl. ¶45 These allegations pertain to pre-suit knowledge.

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

• A primary issue will be one of structural identity: does the accused "modified" wagon contain every single pipe, sleeve, and hinged connection recited in the highly detailed and lengthy Claim 1? The case may turn on whether the modifications made to the product since the prior litigation create a material structural difference sufficient to take it outside the literal scope of the claim's specific architecture.
• A secondary legal question will relate to claim interpretation: is the preamble phrase "with no extra height when folding" a strict and measurable limitation on the claim's scope, or is it a statement of intended purpose whose fulfillment is determined by the presence of the recited structural elements? The answer will dictate whether a small change in height during folding is a viable defense.