Roller Clutch Raceway Geometry for Simultaneous Roller Engagement
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Solution Overview
Problem
Existing roller clutches in hand tools face challenges in achieving simultaneous engagement of rollers for maximum torque transmission due to manufacturing tolerances, leading to partial or uneven engagement, which limits the applied torque and increases production costs.
Innovation Solution
A roller clutch design featuring a rotatable inner race with a cylindrical surface and an outer race with valleys and inclined surfaces, where rollers are biased into a wedging position by springs, ensuring near-simultaneous engagement and uniform pressure distribution, regardless of manufacturing tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If tight tolerances are applied to roller surfaces and roller dimensions to achieve simultaneous engagement, then roller engagement uniformity is improved, but manufacturing cost increases unreasonably
Solution Approach 1:
The patent changes the geometric parameters of the raceways by introducing camber (angular deviation from perpendicularity) and skew (angular deviation from parallelity). Specifically, the first raceway has a camber angle between 1-10 degrees and the second raceway has a skew angle between 1-10 degrees. These parameter changes allow rollers to engage simultaneously without requiring tight manufacturing tolerances, thus resolving the contradiction between engagement uniformity and manufacturing cost
Solution Approach 2:
The patent introduces asymmetric geometric features to the raceways through camber and skew angles. Instead of using symmetric, perpendicular raceways that would require precise tolerance control, the asymmetric cambered and skewed raceways create a self-aligning effect that promotes simultaneous roller engagement while tolerating broader manufacturing variations
2Reliability
If tight tolerances are applied to roller dimensions and surfaces to achieve simultaneous engagement, then torque transmission capability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent modifies the geometric parameters of the raceways by introducing camber and skew angles. The first raceway is cambered at an angle of 1-10 degrees relative to perpendicular, and the second raceway is skewed at an angle of 1-10 degrees relative to parallel. These parameter changes ensure that all rollers engage simultaneously when wedged between the races, enabling maximum torque transmission without requiring complex manufacturing processes or tight tolerances
3Strength
If rollers are wedged between races to prevent relative motion, then locking capability is improved, but dead travel increases when engagement is not simultaneous
Solution Approach 1:
The cambered and skewed raceway geometries perform a preliminary alignment action on the rollers as they approach the engagement position. The camber angle of the first raceway and the skew angle of the second raceway work together to pre-position the rollers for simultaneous engagement, eliminating dead travel and ensuring immediate locking capability when torque is applied
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 design enables near-instantaneous locking and significant torque application with minimized dead travel, maintaining roller integrity and reducing manufacturing costs by compensating for tolerance variations through spring deformation.
Implementation Method 1
springs that bias the rollers into a wedging position with respect to the races
Implementation Method 2
springs that bias the rollers into a wedging position with respect to the races
Implementation Method 3
Roller clutches work by wedging one or more rollers between two surfaces to prevent relative motion between the two surfaces in one direction (a locking direction)
Implementation Method 4
A roller clutch may use spherical rollers such as ball bearings, but using cylindrical rollers is preferred because loads imparted thereon can be distributed along the length of rollers as the cylindrical rollers are wedged between the two surfaces
Data Source
AI summary
A locking clutch having an inner race that is rotatable with respect to an outer race. One of the races is cylindrically shaped and rotates adjacent to a race having valleys. Each valley is connected to an inclined surface. Rollers are located adjacent to the valleys. A cage having fingers may be restrained with respect to the valleys to set the starting position of the rollers. The cage may be selectively restrained to determine the direction in which the rollers are wedged to determine a direction that drives the rollers into contact with both races to lock the races with respect to each other. Rotation of the inner race with respect to the outer race in a direction opposite direction is a free rotating direction. The locking clutch is designed to simultaneously engage all of its rollers to evenly distribute the forces amongst them.