Holding Tank Subassembly With Leak-Free Bucket Interface

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Solution Overview

Problem

Existing holding tanks in recreational vehicles suffer from leakage issues due to numerous connections and high dimensional tolerances, leading to potential damage, increased service costs, and inefficient production and servicing.

Innovation Solution

A subassembly with a bucket-shaped part, seal, and pump arrangement that provides a leak-free interface with the holding tank, minimizing connections and positioning the seal at the highest point to prevent leakage, while integrating key components like pumps and conduits into a unitary structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple connections are made to the holding tank for pumps and subcomponents, then the holding tank can perform multiple functions, but leakage risk increases due to numerous connection points

Engineering Contradiction:
Improvefunctional integrationVSAvoidleakage prevention
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent combines multiple subcomponents (pump, conduit connections, electrical components) into a single integrated subassembly that attaches to the holding tank through one unified interface. This merging eliminates multiple separate connection points, reducing leakage risk while maintaining all necessary functions within the integrated unit.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The subassembly acts as an intermediary component between the holding tank and external systems. It provides a standardized interface that mediates connections for pumps, conduits, and electrical components, isolating the holding tank from multiple direct connections and their associated leakage risks.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of manufacture

If high dimensional tolerances are accepted in holding tank construction, then manufacturing cost decreases, but connection precision deteriorates leading to leakage

Engineering Contradiction:
Improvemanufacturing costVSAvoidconnection precision
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The system is divided into two segments: the holding tank body (manufactured with relaxed tolerances for cost efficiency) and the subassembly (manufactured with tight tolerances for precise connections). This segmentation allows each component to be optimized independently - the tank for low-cost manufacturing and the subassembly for high-precision interfacing.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The subassembly provides a localized area of high precision and quality materials at the interface with the holding tank. While the bulk of the tank can be manufactured with standard tolerances, the critical connection interface achieves high precision through the specially designed subassembly components.

Inventive Principle:
Principle #3Local quality

3Adaptability or versatility

If numerous separate components are used for pumps and conduits, then system adaptability increases, but device complexity increases making servicing difficult

Engineering Contradiction:
Improvesystem flexibilityVSAvoidassembly complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

Multiple functional components (pump motor, pump mechanism, conduit connections, electrical wiring) are merged into a single modular subassembly. This reduces the number of separate parts to manage while maintaining the functional flexibility needed for different pump types and configurations.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The subassembly is designed as a universal interface that can accommodate different pump types, conduit configurations, and electrical connections through standardized mounting points and connection interfaces. This multi-functionality is achieved within a single integrated unit rather than through multiple separate components.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP4172005B1Subassembly for a holding tank with integrated leak free interface to the holding tank
Publication Date: 2025.11.12 THETFORD BV
  • EP4172005B1 patent drawingFigure 1
  • EP4172005B1 patent drawingFigure 2~3
  • EP4172005B1 patent drawingFigure 4

AI summary

A subassembly (200) for a holding tank (202) in combination with a holding tank (202). The subassembly (200) includes a bucket shaped part (206), a seal (214), and a pump arrangement (32). The bucket shaped part (206) defines an inner cavity (212) plus an outer wall (208) and extends through an aperture on the top of the holding tank (202). The seal (214) is disposed at a top portion of the bucket shaped part (206) and enables a leak free seal between the outer wall (208) of the bucket shaped part (206) and the holding tank (202). The pump arrangement (32) is located at a lowest portion of the bucket shaped part (206).