Dishwasher Spray Arm Coding Geometry for Single-Position Assembly

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Solution Overview

Problem

Existing household dishwashers face challenges in ensuring correct assembly and disassembly of the spray arm, which can lead to incorrect positioning and potential operational issues, often requiring additional sensors for angular position detection.

Innovation Solution

The implementation of a rib geometry with a coding groove on the spray arm and a corresponding coding rib on the pump pot allows the spray arm to be mounted and removed in a single angular position, eliminating the need for additional sensors by ensuring precise alignment during assembly and disassembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If additional sensors are provided on the spray arm to detect angular position, then measurement precision is improved, but device complexity increases

Engineering Contradiction:
Improveangular position detectionVSAvoidsensor provision
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The spray arm assembly performs its own angular position detection function through the interaction between the coding groove on the spray arm and the coding rib on the pump bowl. This mechanical self-service system eliminates the need for external sensors, as the structure itself provides the positioning information through its geometric features during assembly and operation.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The coding groove and coding rib act as intermediary elements that mediate between the spray arm and pump bowl. These geometric features serve as the interface for angular position determination, replacing the need for electronic sensors while providing reliable mechanical positioning and detection functionality.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If the spray arm can be freely assembled at any angular position, then ease of operation is improved, but reliability deteriorates due to incorrect installation

Engineering Contradiction:
Improveassembly convenienceVSAvoidcorrect installation
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The coding groove on the spray arm and the corresponding coding rib on the pump bowl create an asymmetric geometric relationship. This asymmetry ensures that the spray arm can only be assembled in one correct angular position, preventing incorrect installation while maintaining ease of assembly through the simple mechanical guidance provided by these asymmetric features.

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The coding groove and coding rib are pre-configured in specific angular positions during manufacturing. This preliminary action of pre-positioning the geometric features ensures that when assembly occurs, the correct angular alignment is automatically achieved without requiring additional adjustment or verification steps by the user.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP4003129B1Domestic dishwasher
Publication Date: 2024.09.18 BSH HAUSGERATE GMBH
  • EP4003129B1 patent drawingFigure 1
  • EP4003129B1 patent drawingFigure 2
  • EP4003129B1 patent drawingFigure 3

AI summary

The invention relates to a domestic dishwasher (1) comprising a washing container (2), a spray arm (16) for applying washing liquor and/or fresh water (F) to the dishwasher load held in the washing container (2), a drive system (34) for actively driving the spray arm (16), and a pump can (29), on which the spray arm (16) is rotatably mounted about an axis of rotation (26), wherein said spray arm (16) has a rib geometry (27) that revolves around the axis of rotation (26) and that has a position encoding groove (28) running along the axis of rotation (26), and the pump can (29) has a position encoding rib (33) running along the axis of rotation (26) and corresponding to the position encoding groove (28), which rib can be guided through the position encoding groove (28) along the axis of rotation (26) during the assembly and disassembly of the spray arm (16), so that the spray arm (16) can be assembled on and disassembled from the pump can (29) in precisely one angular position.