Feed Screw Bearing Assembly for Precise Micro-Volume Dispensing
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Solution Overview
Problem
Conventional fluid dispense pumps experience excessive radial and axial play due to gaps between the spanner nut and the bearing assembly, leading to inconsistent fluid output and clogging issues during micro-volume dispensing operations.
Innovation Solution
The implementation of a feed screw assembly with a bearing assembly that includes an outer ring directly abutting the spanner nut and an inner ring rotating relative to the outer ring, along with a spring-loaded spanner nut and a load washer, to minimize axial play and ensure precise fluid dispensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional feed screw assembly with gaps between the spanner nut and bearing assembly is used, then the device complexity is reduced, but radial and axial play increases leading to inconsistent fluid output
Solution Approach 1:
A feed screw shaft is introduced as an intermediary component between the feed screw and the bearing assembly. The shaft extends from the feed screw and rotates within the bearing assembly, providing a stable rotational interface that reduces radial and axial play while maintaining the functional relationship between the feed screw and pump chamber
Solution Approach 2:
The feed screw assembly is segmented into distinct functional components: the feed screw for material transport, the feed screw shaft for rotational movement, and the bearing assembly for support. This segmentation allows each component to be optimized for its specific function while reducing overall play in the system
2Manufacturing precision
If the inner ring of the bearing assembly directly contacts the spanner nut to eliminate gaps, then axial play is reduced, but friction increases potentially affecting rotation smoothness
Solution Approach 1:
The feed screw shaft acts as a mediator between the inner ring and the spanner nut. The shaft extends through the bearing assembly and contacts the spanner nut, while the inner ring rotates on the shaft with minimal clearance. This intermediary arrangement allows the spanner nut to be securely positioned against the outer ring while the inner ring maintains smooth rotation on the shaft with reduced friction
Solution Approach 2:
The direct contact mechanism between the inner ring and spanner nut is replaced with an intermediary shaft-based system. The shaft provides a dedicated rotational interface that separates the axial positioning function (handled by the spanner nut against the outer ring) from the rotational function (handled by the inner ring on the shaft), reducing friction while maintaining precision
Data Source
AI summary
Provided is a feed screw assembly for a fluid dispense pump, comprising a feed screw; a feed screw shaft extending from the feed screw; a spanner nut about the feed screw shaft; a bearing assembly about the feed screw shaft between the spanner nut and the feed screw The bearing assembly includes an outer ring that directly abuts the spanner nut; and an inner ring that rotates inside and relative to the outer ring, wherein the inner ring is coupled to the feed screw shaft for rotating the feed screw, and wherein the inner ring is separated from the spanner nut by a gap.