Hong Kong Uking Trading Ltd v. Zhejiang Hengfeng Top Leisure Co Ltd

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Hong Kong Uking Trading Limited (Hong Kong)
  • Defendant: Zhejiang Hengfeng Top Leisure Co., Ltd. (People's Republic of China)
  • Plaintiff’s Counsel: Carlson IP Law, LLC
• Case Identification: 8:26-cv-2635, M.D. Fla., 09/11/2026
• Venue Allegations: Venue is alleged to be proper because Defendant does not reside in the United States and may be sued in any judicial district. The complaint also asserts that a substantial part of the events giving rise to the claim, including the threatened removal of products sold to customers in the district, occurred in the Middle District of Florida.
• Core Dispute: Plaintiff seeks a declaratory judgment that its foldable utility wagon does not infringe Defendant’s patent related to a foldable wagon, and further seeks a declaration that the patent is invalid.
• Technical Context: The technology concerns mechanical improvements to foldable utility wagons, a common consumer product, focusing on a collapsing mechanism that maintains a constant vertical height for more compact storage.
• Key Procedural History: The action was precipitated by Defendant’s use of Amazon's Patent Evaluation Express (APEX) program to accuse Plaintiff’s product of infringement, creating an immediate threat of the product’s removal from the Amazon marketplace. The complaint alleges that the patent-in-suit was allowed only after amendments were made during prosecution to add specific structural limitations, and it further challenges the patent's claimed priority date.

Case Timeline

Date	Event
2020-03-25	'178 Patent Priority Date
2020-09-18	'178 Patent Application Filing Date
2022-05-17	'178 Patent Issue Date
2026-08-28	Defendant submits APEX complaint against Plaintiff
2026-09-11	Complaint for Declaratory Judgment Filed

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

U.S. Patent No. 11,332,178 - "Foldable Wagon"

• Patent Identification: U.S. Patent No. 11,332,178, "Foldable Wagon," issued on May 17, 2022 (the “’178 Patent”). Compl. ¶13

The Invention Explained

• Problem Addressed: The patent background describes a need for a hand-drawn wagon that can be collapsed for storage into a relatively smaller volume than conventional foldable wagons, specifically by not increasing in vertical height when collapsed. ʼ178 Patent, col. 1:11-20
• The Patented Solution: The invention is a wagon with a frame featuring folding bar assemblies on its sides. The frame is designed so that when it is collapsed, the lower ends of the folding bars slide downward along vertical poles while the upper ends remain fixed. This action allows the wagon to shrink in length and width while its vertical height remains substantially the same between the expanded and collapsed states. ʼ178 Patent, abstract ʼ178 Patent, col. 3:6-54
• Technical Importance: This design seeks to create a more space-efficient product for storage by maintaining a constant, minimal height profile when folded. ʼ178 Patent, col. 1:15-20

Key Claims at a Glance

• The complaint identifies independent claims 1, 3, and 10 as being at issue. Compl. ¶14
• Independent Claim 1 recites, among other things:
  • A frame with sides formed by folding bar assemblies, where lower leg ends are "operatively slidingly connected" to vertical poles.
  • A "collapsible bottom support assembly" that "comprises a central hub and four bars."
• Independent Claim 3 recites a similar frame structure and adds:
  • A "tow handle" that is "connected to two of the vertically oriented poles via two connecting members."
• Independent Claim 10 recites a structure highly similar to Claim 1, including the "collapsible bottom support assembly" with a "central hub and four bars." Compl. ¶16 '178 Patent, claims 1, 3, 10
• The complaint focuses on the independent claims, stating that because the accused product does not meet limitations of the independent claims, it "cannot infringe those claims or any claim that depends from them." Compl. ¶28

III. The Accused Instrumentality

Product Identification

• The accused product is the "Uking Wagon," identified as a "Sekey-brand foldable utility wagon" sold on Amazon.com under identifiers including ASIN B0G6KKQ74R. Compl. ¶12

Functionality and Market Context

• The complaint describes the Uking Wagon as a "collapsible four-wheeled cart with a fabric liner and a pull handle." Compl. ¶12 It is characterized as being "of a common design sold by many manufacturers," suggesting it represents a standard, non-patented configuration. Compl. ¶12 The complaint’s technical description is primarily a denial of infringement; it alleges the Uking Wagon does not contain the specific "central hub" bottom support assembly of claims 1 and 10, nor the specific "two connecting members" for the pull handle as required by claim 3. Compl. ¶28
• No probative visual evidence provided in complaint.

IV. Analysis of Infringement Allegations

The complaint is for declaratory judgment, so the following table summarizes the plaintiff's (Uking's) allegations of non-infringement.

’178 Patent Infringement Allegations

Claim Element (from Independent Claim 1)	Alleged Non-Infringing Functionality	Complaint Citation	Patent Citation
a collapsible bottom support assembly, the bottom support assembly comprises a central hub and four bars, the four bars are each operatively pivotally connected to the central hub and operatively pivotally connected to the bottom end portion of a respective one of the vertically oriented poles	The complaint alleges, by way of example, that the Uking Wagon does not include the "collapsible bottom support assembly . . . comprising a central hub . . . and four bars" as required by the claim.	¶28	col. 4:1-10

’178 Patent Infringement Allegations

Claim Element (from Independent Claim 3)	Alleged Non-Infringing Functionality	Complaint Citation	Patent Citation
a tow handle operatively connected to the frame wherein the tow handle is connected to two of the vertically oriented poles via two connecting members...	The complaint alleges, by way of example, that the Uking Wagon does not include the "pull handle . . . connected to two of the vertical uprights . . . by two connecting members" as required by the claim.	¶28	col. 4:39-46

• Identified Points of Contention:
  • Structural Mismatch: The core of Uking's non-infringement argument centers on specific mechanical structures. The primary questions for the court will be factual: does the Uking Wagon's bottom support structure contain a "central hub" with "four bars" as claimed, and does its handle attach via "two connecting members" as claimed? Uking's position is that its wagon, being of a "common design," lacks these specific, allegedly inventive features. Compl. ¶12 Compl. ¶28
  • Prosecution History: The complaint highlights that these specific limitations were added to the claims to secure allowance from the patent office. Compl. ¶17 This raises the question of whether prosecution history estoppel might limit the patentee's ability to argue that different structures in the Uking Wagon are equivalent to the claimed structures.

V. Key Claim Terms for Construction

1. The Term: "collapsible bottom support assembly ... comprising a central hub and four bars"

   • Context and Importance: This limitation appears in independent claims 1 and 10 and was allegedly added to overcome a rejection during prosecution. Compl. ¶17 Uking’s non-infringement case for these claims rests on the assertion that its product lacks this feature. Compl. ¶28 The interpretation of this term will therefore be dispositive for those claims.
   • Evidence for a Broader Interpretation: A party could argue that the term should cover any bottom support mechanism that uses a central pivot point and radiating bars to support a load, pointing to the described function of preventing the liner from carrying the full cargo weight. '178 Patent, col. 4:15-18
   • Evidence for a Narrower Interpretation: The specification discloses a specific embodiment with a "central hub 58" and "four bars 56." '178 Patent, Fig. 17 '178 Patent, col. 4:1-10 The fact this limitation was added to gain allowance may suggest that the term should be narrowly construed to cover only structures closely resembling the one disclosed, potentially creating a file history estoppel. Compl. ¶17

2. The Term: "two connecting members"

   • Context and Importance: This term from independent claim 3 defines how the pull handle attaches to the wagon frame. Like the "central hub" assembly, this feature was also allegedly added to secure allowance, making its construction critical for claim 3. Compl. ¶17 Uking alleges its wagon does not have this structure. Compl. ¶28
   • Evidence for a Broader Interpretation: A party might argue that any pair of linkages pivotally connecting the handle to the frame falls within the scope of this term.
   • Evidence for a Narrower Interpretation: The patent shows and describes a specific arrangement where "connecting members 60" are configured to "extend downward in a sloped manner" from the frame to the handle. '178 Patent, Fig. 13 '178 Patent, col. 4:46-55 This specific geometry could be argued to be a definitional aspect of the term, limiting its scope to that particular configuration.

VI. Other Allegations

• Indirect Infringement: The complaint includes a blanket denial of any direct or indirect infringement. Compl. ¶27 As a declaratory judgment action filed by the accused infringer, it does not plead facts supporting such a claim but rather denies liability on all grounds.
• Willful Infringement: Willfulness is not alleged by the plaintiff. However, Uking requests that the court declare the case "exceptional" and award attorneys' fees. Compl. ¶D, p. 13 The basis for this appears to be the allegation that Hengfeng is asserting a patent that "it should never have obtained to shut down a lawful competitor," and that the features distinguishing the patent were already known in the art. Compl. ¶2 Compl. ¶34

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

This declaratory judgment action appears to center on three main issues for the court to resolve:

1. Claim Scope and Prosecution History: A primary issue will be the scope of the claims, particularly the limitations allegedly added during prosecution. The case may turn on how narrowly the terms "collapsible bottom support assembly... comprising a central hub" and "two connecting members" are construed in light of the patent's specification and the statements made to the patent office to secure allowance.

2. Structural Comparison: A key evidentiary question will be one of structural difference: can Uking prove that its "common design" wagon lacks the specific mechanical structures required by the claims? This will involve a direct factual comparison between the accused product's construction and the court's interpretation of the claim language.

3. Validity and Prior Art: A parallel battleground will be Uking’s invalidity challenge. The court will have to consider whether Uking can prove, by clear and convincing evidence, that the asserted claims are obvious in light of prior art that it alleges the examiner did not properly consider or apply. Compl. ¶¶33-34 Uking's challenge to the patent's priority date could, if successful, expand the body of available prior art. Compl. ¶35