Roller Clutch Cage Layout 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 during torque transmission due to manufacturing tolerances, leading to partial or uneven engagement, which limits the applied torque and results in unnecessary dead travel.
Innovation Solution
The design incorporates an inner and outer race with inclined surfaces and rollers held by a cage, where springs bias the rollers into a wedging position, ensuring nearly simultaneous engagement and uniform load distribution, facilitated by a shifting mechanism to adjust the wedging direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tight tolerances are used on roller surfaces and rollers to achieve simultaneous engagement, then torque transmission capability is improved, but manufacturing cost increases unreasonably
Solution Approach 1:
The patent applies preliminary action by pre-positioning the rollers at specific locations on the inner race surface before engagement. The rollers are placed at predetermined angular positions (e.g., 90 degrees apart) that ensure simultaneous engagement with the outer race lobes, eliminating the need for tight manufacturing tolerances on roller and race surfaces.
Solution Approach 2:
The patent changes the geometric parameters of the race surfaces by introducing lobes with specific angular spacing and corresponding roller positions. This parameter modification transforms the engagement mechanism from one requiring precise surface tolerances to one where geometry itself ensures simultaneous contact, resolving the manufacturing cost issue.
2Reliability
If tight tolerances are used on rollers and mating surfaces to achieve simultaneous engagement, then torque transmission is improved, but manufacturing complexity increases
Solution Approach 1:
The design pre-positions rollers at specific angular locations on the inner race, ensuring that when the races engage, all rollers contact their corresponding outer race lobes simultaneously. This preliminary positioning at defined geometric locations eliminates the need for tight tolerances on roller dimensions and mating surfaces.
Solution Approach 2:
The patent introduces asymmetric lobe geometry on the outer race with specific angular spacing that corresponds to asymmetric roller positioning on the inner race. This asymmetric design creates predetermined engagement points that ensure simultaneous contact without requiring symmetric, high-precision manufacturing of all components.
3Ease of manufacture
If only partial engagement of rollers is achieved due to tolerance variations, then device complexity is reduced, but torque transmission capability is limited
Solution Approach 1:
The patent pre-positions multiple rollers at specific angular intervals (e.g., 90 degrees) on the inner race surface. This preliminary arrangement ensures that when the outer and inner races engage, all rollers contact their corresponding lobes simultaneously, maximizing torque transmission capability while accommodating standard manufacturing tolerances.
Solution Approach 2:
The patent combines multiple rollers into a single integrated system where all rollers are positioned relative to each other on the inner race. This merging of multiple engagement points into a coordinated system ensures that torque is distributed across all rollers simultaneously, achieving high torque transmission without requiring individual precision adjustment of each roller.
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 achieves near-instantaneous locking and uniform torque application, minimizing dead travel and preventing brinelling, while accommodating manufacturing tolerances through load balancing mechanisms.
Implementation Method 1
Each valley is connected to a corresponding inclined surface that is adjacent to each valley. Rotation of the inner race with respect to the outer race in one direction induces the rollers to roll away from the corresponding valleys along the inclined surface.
Implementation Method 2
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), thereby providing for the application of torque in the locking direction.
Implementation Method 3
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 facets. Rollers are located adjacent to the facets. A cage having fingers may be restrained with respect to the facets 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.