Bi-directional Overrunning Clutch Split Roll Cage Drag Mechanism
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Solution Overview
Problem
Current bi-directional overrunning clutches for primary drive axles in machinery like snowblowers and all-terrain vehicles are complex and unreliable, with a risk of reverse engagement when using a split roll cage configuration, which can cause unintended torque transmission.
Innovation Solution
A bi-directional overrunning clutch design featuring a housing with coaxially aligned hubs, roller assemblies with roll cages, and an intermittent coupler that allows limited rotation and axial movement of the roll cages, preventing reverse engagement by using radially extending coupler teeth that fit into slots, ensuring rollers engage only with the forward or reverse cam surfaces as needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a split roll cage configuration is used in a bi-directional overrunning clutch, then the clutch can accommodate larger manufacturing tolerances and torque differences between axles, but there is a risk of reverse engagement that can cause unintended torque transmission
Solution Approach 1:
A drag mechanism is introduced as an intermediary component between the rollers and the roll cage. This drag mechanism includes a drag member that contacts the roll cage and a drag spring that biases the drag member to create frictional contact. This intermediary frictional connection prevents the roll cage from rotating in reverse while still allowing the split configuration to accommodate manufacturing tolerances and torque differences.
Solution Approach 2:
The drag spring is pre-compressed to create a preliminary frictional force that opposes potential reverse rotation of the roll cage. This preliminary anti-action through frictional resistance prevents reverse engagement before it can occur, while maintaining the benefits of the split roll cage design for accommodating tolerances and torque variations.
2Adaptability or versatility
If an intermittent coupler is used to allow limited rotation of roll cages relative to each other, then the clutch can handle varying speed conditions, but the structure becomes more complex
Solution Approach 1:
The intermittent coupler is segmented into discrete teeth that engage with corresponding slots in the roll cages. This segmentation allows the coupler to permit limited rotation in controlled increments while preventing continuous relative rotation. The segmented tooth-slot engagement provides a simple yet effective mechanism for handling varying speed conditions without requiring complex continuous control systems.
3Reliability
If friction disk mechanisms are used to index roller assemblies relative to hubs, then positive driving engagement is maintained, but the device complexity increases
Solution Approach 1:
The friction disk mechanisms utilize the existing rotational motion and friction forces within the clutch assembly to automatically index the roller assemblies relative to the hubs. The friction between the friction disks and contacting surfaces creates self-aligning forces that position the rollers correctly without requiring additional actuation mechanisms, thereby maintaining positive driving engagement while minimizing added complexity.
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 enhances reliability and prevents reverse engagement, allowing for efficient torque transmission while maintaining positive driving engagement, even under varying speed conditions, and accommodates larger manufacturing tolerances and torque differences between axles.
Implementation Method 1
The friction plate is engaged with or formed on the roll cage so as to rotate in combination with the roll cage, and is positioned to contact a contact surface on the hub. The spring is compressed between the end cap and the roll cage for biasing the friction member into frictional contact with the contact surface of the hub.
Implementation Method 2
The spring is compressed between the end cap and the roll cage for biasing the friction member into frictional contact with the contact surface of the hub.
Implementation Method 3
The rollers surrounding each hub are spaced about an associated hub and adapted to wedgingly engage between the hub and the inner cam surface when one of the hubs and the housing is rotated with respect to the other of the hubs.
Implementation Method 4
The housing includes an inner cam surface. The rollers surrounding each hub are spaced about an associated hub and adapted to wedgingly engage between the hub and the inner cam surface.
Data Source
AI summary
A bi-directional overrunning clutch includes a housing and a pair of hubs substantially coaxially aligned within the housing. A pair of roll cages position a plurality of rollers between each hub and an inner cam surface of the housing. The rollers are positioned to wedge between the hub and the inner cam surface when one of the hub and the housing is rotated with respect to the other. End caps are attached to the housing adjacent to the hubs. A friction disk mechanism includes a friction plate rotating in combination with each the roll cage and a spring compressed between the end cap and the roll cage for biasing the friction member into frictional contact with the hub. An intermittent coupler is located between each roll cage and configured to engage the roll cages so as to permit indexing of one roll cage relative to the other.