Dialysis Machine Door Handle Form-Fit Locking for Seal Positioning
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Solution Overview
Problem
Medical appliances, such as acute dialysis machines, face issues with door handles that yield under force, providing a negative quality impression and compromising the seal during movement, due to manufacturing tolerances and inexpensive sheet-metal constructions.
Innovation Solution
A handle mechanism with form-fit units, including tapered spigots and conical receptacles, and spring means, ensures defined positioning and force transmission without handle displacement, compensating manufacturing tolerances and maintaining a secure seal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a simple sheet-metal construction with conventional door handle is used, then manufacturing cost is reduced, but the handle yields under force providing a negative quality impression
Solution Approach 1:
The door assembly combines a sheet-metal door with a plastic insert containing the form-fit unit. This composite construction allows the door to maintain rigidity when pushed, as the plastic insert with the form-fit means provides structural support, while still allowing cost-effective manufacturing using conventional sheet-metal and plastic molding processes.
2Device complexity
If a conventional door handle is used, then the construction remains simple, but the seal is deformed when pushing the dialysis machine
Solution Approach 1:
The form-fit unit is pre-assembled into the door during manufacturing, establishing a fixed geometric reference before the door is installed. This preliminary positioning ensures that when the door is closed, the seal is correctly positioned and compressed uniformly against the housing, compensating for manufacturing tolerances without requiring complex adjustment mechanisms.
Solution Approach 2:
The invention replaces complex mechanical adjustment systems with a geometric form-fit connection. Instead of using adjustable mounts or complex positioning mechanisms, the tapered spigot and conical receptacle provide self-aligning, tolerance-compensating positioning through their geometric shapes, simplifying the overall construction while improving precision.
3Ease of manufacture
If the door and housing have manufacturing tolerances, then production is easier and cheaper, but the door may not close correctly or the handle may have clearance
Solution Approach 1:
The form-fit unit uses a tapered geometry where the spigot diameter varies along its length. This parameter change allows the connection to accommodate radial and angular misalignments caused by manufacturing tolerances. The taper provides a gradual engagement that self-corrects positioning errors, ensuring accurate door closure despite variations in door and housing dimensions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a handle that feels massive and rigid, ensuring correct door closure and uniform seal pressure, while allowing for easy opening and closing, and transmitting thrust forces effectively to the housing.
Implementation Method 1
spring means (28), by means of which the at least one form-fit means (32) can be pretensioned
Implementation Method 2
tapered spigots (32) and/or conical receptacles (30) which are firmly connected to one another on closing
Data Source
AI summary
A medical appliance, in particular an apparatus for extracorporeal blood treatment, has a housing including a door and with a handle mechanism arranged at the door, via which the door can be locked with the housing via a locking mechanism. A part of the locking mechanism is formed at the handle mechanism in a part thereof that protrudes into the housing. A form-fit unit includes at least one form-fit element and at least one form-fit element counterpart, such that on locking and/or closing the door, the at least one form-fit element at least partly engages in the at least one form-fit element counterpart.