Disposable Dental Angle Gear Axial Support Design
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Solution Overview
Problem
Disposable dental prophylaxis angles suffer from unwanted noise, vibration, and premature wear due to the lack of axial support for the drive gear, and contra-angles are prone to shaft over-flexing and breakage due to their bent design, which disrupts dental procedures and requires frequent replacement.
Innovation Solution
A dental prophylaxis angle design featuring a body with a sleeve, neck, and head, including a circumferential groove and lip to secure the drive gear, and a cradle to prevent lateral movement of the shaft, ensuring proper meshing and reducing vibrations, while a flexible shaft accommodates various angles without over-flexing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the drive gear is left floating within the body without axial support, then the assembly is simpler and easier to manufacture, but unwanted noise and vibration occur due to contact between the drive gear and the shaft of the driven gear
Solution Approach 1:
The patent employs a disposable angle design where the body includes integrated support structures (lip and cradle) that are molded as single-use components. These structures provide axial support to prevent gear contact and noise without requiring complex reusable support mechanisms, aligning with the disposable nature of the product.
Solution Approach 2:
The support functions are merged into the body structure itself. The lip and cradle are integral parts of the body, combining the body's structural role with the additional function of providing axial support and preventing gear contact, thereby eliminating the need for separate support components.
2Object-generated harmful factors
If a finger is added to the cap to prevent axial movement of the drive gear, then unwanted contact between gears is reduced, but the finger does not provide adequate axial support because it is located at the top of the angle rather than the bottom
Solution Approach 1:
Instead of placing the support structure at the top of the angle (as in the finger approach), the patent inverts the approach by locating the lip and cradle at the bottom of the body. This inverted positioning provides proper axial support from the correct location to prevent gear contact effectively.
Solution Approach 2:
The support function is extracted from the cap (where the finger approach failed) and relocated to the body structure itself. The lip and cradle are separate functional elements within the body that specifically address axial support without relying on the cap structure.
3Adaptability or versatility
If the shaft is allowed to accommodate various angles through flexibility, then adaptability is improved, but the shaft becomes prone to over-flexing and breakage in contra-angles
Solution Approach 1:
The cradle provides preliminary support to the shaft before excessive flexing can occur. By preventing lateral movement and providing a stopping point for shaft deflection, the cradle counteracts the tendency toward over-flexing and breakage before it happens during normal operation.
Solution Approach 2:
The shaft is designed with flexible properties to accommodate angular variations, but the cradle provides a structural constraint that prevents excessive flexing. This combination allows necessary flexibility for adaptability while maintaining strength through the cradle's support.
Data Source
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AI summary
A dental prophylaxis angle comprises a drive gear, a driven gear and a hollow body. The drive gear has drive gear teeth, a circumferential groove and an intermediate portion having an angled leading edge. The driven gear has a shaft and driven gear teeth for engagement with said drive gear teeth. The hollow body is for receiving said drive gear and said driven gear, said body having a front end and a rear end and including a lip engaged by said drive gear groove for retaining said drive gear within said body, said angled leading edge adapted to engage said lip to allow insertion of said drive gear into said body from said front end of said body until said lip is engaged by said drive gear groove.