Soluble Spacer Method for Miniature Pump Clearance
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Solution Overview
Problem
Miniature gear pump-heads face challenges in manufacturing lightweight, durable materials that are cost-effective and maintain dimensional stability, as well as issues with tolerance stack-up, alignment, and static seals, which are exacerbated by miniaturization, leading to difficulties in achieving precise clearances and reliability.
Innovation Solution
The method involves using soluble spacers of defined thickness to establish desired clearances between rotary members and housing portions, which are then dissolved to ensure precise fit and alignment, reducing the need for mechanical fasteners and alignment pins, and using adhesive bonding or other techniques to secure the housing portions while applying preload to ensure consistent clearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional metal materials are used for pump-head housing, then dimensional stability and durability are improved, but weight and manufacturing cost increase
Solution Approach 1:
The patent employs composite materials consisting of thermoset plastic matrix reinforced with fibers (such as glass, carbon, or aramid fibers). This composite structure provides dimensional stability and durability comparable to metal while significantly reducing weight. The fiber reinforcement prevents warping and maintains geometric integrity during curing and operation, resolving the contradiction between weight reduction and dimensional stability.
2Weight of moving object
If plastic materials are used for pump-head housing, then weight and manufacturing cost are reduced, but dimensional stability and structural strength worsen
Solution Approach 1:
The patent employs composite materials consisting of thermoset plastic matrix reinforced with fibers (such as glass, carbon, or aramid fibers). This composite structure provides dimensional stability and durability comparable to metal while significantly reducing weight. The fiber reinforcement prevents warping and maintains geometric integrity during curing and operation, resolving the contradiction between weight reduction and dimensional stability.
3Manufacturing precision
If dimensional tolerances are tightened for miniature pump parts, then manufacturing precision is improved, but manufacturing cost and difficulty increase
Solution Approach 1:
The patent divides the pump-head housing into multiple separately moldable portions (first housing portion, second housing portion, and optionally third housing portion). Each portion can be molded independently with relaxed tolerances, then assembled together. This segmentation allows achieving tight overall tolerances through accumulation of less stringent individual tolerances, significantly reducing manufacturing difficulty and cost while maintaining precision.
Solution Approach 2:
The patent introduces soluble spacers as intermediary elements during assembly. These spacers are placed between housing portions to precisely control the positioning and clearance of rotary members. The spacers are later dissolved (by water or other solvents) to leave the desired clearance without requiring tight mechanical tolerances on the housing portions themselves, thereby reducing manufacturing difficulty while achieving precision.
4Reliability
If mechanical fasteners and alignment pins are used, then assembly reliability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent eliminates mechanical fasteners (screws, clips, snap-fits) and alignment pins from the assembly. Instead, housing portions are bonded together using adhesive bonding or other bonding techniques. This extraction of mechanical fastening elements reduces parts count and device complexity while maintaining assembly reliability through proper bonding procedures and design features such as bonding surfaces and alignment features integrated into the molded parts.
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
This approach allows for the production of reliable, miniaturized, hermetically sealed, magnetically driven pumps with reduced parts count and cost, achieving precise clearances and tolerances consistently, suitable for high-volume production.
Implementation Method 1
the soluble spacer is dissolved to provide the desired clearance of the rotary member in the pump-cavity
Implementation Method 2
The housing portions are attached together to form the pump-cavity containing the rotary member(s)
Data Source
AI summary
Various methods are disclosed for manufacturing pump-heads having a housing enclosing at least one rotary member. In an exemplary method first and second housing portions are provided that collectively, when assembled, define a pump-cavity that accommodates the rotary member(s). The rotary member(s) is assembled into the pump-cavity, along with at least one soluble spacer of a defined thickness that corresponds to a desired clearance of the rotary member relative to the pump-cavity. The spacer contacts a surface of the rotary member facing a corresponding surface of the housing portion. The first and second housing portions are attached together to form the pump-cavity containing the rotary member(s). The soluble spacer is dissolved to provide the desired clearance of the rotary member in the pump-cavity. As the housing portions are attached together, e.g., by adhesive bonding, the spacer establishes the desired clearance of the rotary member(s) in the pump-cavity.