Spring-Driven Pump Rack and Pinion Jamming Prevention
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Solution Overview
Problem
Oral cleaning devices that produce user-adjustable coordinated bursts of liquid and air are prone to jamming or locking due to the rapidity of the repeating motion of the mechanism, which affects their operational efficiency and effectiveness in removing dental plaques and biofilms.
Innovation Solution
A spring-driven pump assembly with a rack and pinion drive mechanism is designed, featuring a rack with teeth having a forward-pitch geometry and a pinion with a first tooth of reduced height, along with angled and pointed or rounded tips, to reduce the likelihood of misalignment and jamming, allowing for user-adjustable coordinated bursts of liquid and air.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If rapid repeating motion is used to produce multiple bursts per actuation, then productivity is improved, but reliability deteriorates due to jamming and locking
Solution Approach 1:
The rack teeth are designed with dynamic geometry features including angled front and rear surfaces with different angles, and pointed or rounded tips. This dynamic tooth geometry allows the rack and pinion mechanism to adapt during rapid cycling, reducing the likelihood of misalignment and jamming while maintaining high-speed operation for multiple bursts per actuation.
Solution Approach 2:
The invention changes the geometric parameters of the rack teeth by providing angled front surfaces and angled rear surfaces with different angles, and pointed or rounded tips. This parameter modification optimizes the engagement characteristics during rapid motion, enabling high productivity while preventing the mechanism from locking or jamming.
2Ease of manufacture
If conventional rack and pinion geometry is used, then ease of manufacture is improved, but reliability deteriorates due to misalignment and jamming
Solution Approach 1:
The rack teeth are provided with local geometric modifications including angled front surfaces, angled rear surfaces with different angles, and pointed or rounded tips. These localized quality changes at critical tooth surfaces improve engagement reliability during rapid cycling while maintaining overall manufacturability of the rack and pinion assembly.
Solution Approach 2:
The rack teeth feature asymmetric geometry where the front surface angle differs from the rear surface angle. This asymmetric design optimizes the engagement and disengagement characteristics during rapid motion cycles, reducing misalignment and jamming while remaining manufacturable using standard machining processes.
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 improved design enhances the operational reliability and effectiveness of oral cleaning devices by reducing the likelihood of jamming and locking, enabling efficient delivery of coordinated bursts of liquid and air for superior dental plaque and biofilm removal.
Implementation Method 1
a compressible spring configured to exert a forward force on the plunger assembly
Implementation Method 2
a rack and pinion assembly configured to exert a force on the plunger assembly opposite the forward force
Data Source
AI summary
An oral care device (10) with a pump assembly (12) including: a plunger assembly (52) having a rack assembly (74); a compressible spring (64) configured to exert a forward force on the plunger assembly; and a rack and pinion assembly (72) configured to exert a force on the plunger assembly opposite the forward force, wherein the rack assembly includes a plurality of rack teeth (74a . . . 74g) and the pinion assembly (76) includes a plurality of teeth (78) arranged around a portion of the pinion; where the plurality of rack teeth include an angled front surface (86) and an angled rear surface (87), the front surface of at least some of the plurality of rack teeth including a different angle than the rear surface, and further where at least some of the plurality of rack teeth include a pointed or rounded tip (82).