Wheel Speed Control Hub With Recesses for Debris Isolation
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Solution Overview
Problem
Conventional speed control devices for vehicles like rollators suffer from performance degradation and abnormal noise due to foreign matter generated by the interaction of brake drums and gears, which increases sliding resistance and friction.
Innovation Solution
A speed control device with a tubular boss portion that includes recesses on its inner circumferential surface to trap foreign matter, preventing it from spreading and maintaining lubrication between the shaft and boss portion, thereby reducing performance degradation and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a brake drum and brake shoe are used to control wheel speed, then speed control function is achieved, but foreign matter is generated that increases sliding resistance and causes performance degradation
Solution Approach 1:
The inner circumferential surface of the boss portion is segmented into multiple regions by forming circumferential grooves at different positions. This segmentation creates separate storage spaces for foreign matter, preventing it from accumulating and spreading across the entire sliding surface, thereby maintaining lubrication effectiveness and reducing sliding resistance.
2Speed
If gears are used to increase wheel speed, then speed multiplication is achieved, but wear powders are generated that contaminate the lubrication area
Solution Approach 1:
The harmful wear powders generated by gear meshing are extracted from the lubrication area by directing them into the circumferential grooves on the boss portion. The grooves act as collection channels that separate contaminants from the lubricant film between the shaft and boss, preventing lubricant degradation and maintaining smooth rotation.
3Force
If lubricant is applied between shaft and boss portion, then sliding resistance is reduced, but foreign matter accumulates and degrades lubrication effectiveness
Solution Approach 1:
The boss portion is given non-uniform local quality through the circumferential grooves, creating zones with different functions: smooth sliding surfaces for low friction and grooved zones for contaminant storage. This local differentiation allows the lubricant to maintain effectiveness in the sliding areas while foreign matter is isolated in the groove regions.
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 device effectively prevents performance degradation and abnormal noise by containing foreign matter and maintaining lubrication, ensuring smooth operation.
Implementation Method 1
lubricant is applied between an outer circumferential surface of the shaft and the boss portion. This reduces the sliding resistance of the boss against the axle
Implementation Method 2
the rotation of the wheel is increased by the gear mechanism and transmitted to the gear plate, as a result of which the brake shoe is subjected to a centrifugal force. This causes the brake shoe to forcibly abut against the inner circumferential surface of the brake drum
Data Source
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AI summary
An aspect of the present invention provides a speed control device (1, 201, 301, 401, 501) including: an axle (2) supporting a wheel (103); a tubular boss portion (41) rotatably supporting the axle (2); lubricant applied at least between an outer circumferential surface (2a) of the axle (2) and an inner circumferential surface (41b) of the boss portion (41); and a brake mechanism (20, 220, 420, 520) integrated with the boss portion (41), the brake mechanism (20, 220, 420, 520) being configured to control rotation of the wheel (103) depending on the rotation speed of the wheel (103). Recesses (43a, 43b) are formed in at least one of (i) a supported outer circumferential surface (2b) of the outer circumferential surface (2a) of the axle (2), the supported outer circumferential surface (2b) being supported by the boss portion (41), or (ii) an inner circumferential surface (41b) of the boss portion (41).