Overrunning One-Way Clutch with Segmented Struts for Reduced Lubrication
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Solution Overview
Problem
Existing one-way clutches in vehicular automatic transmissions require significant lubricating fluid to dampen struts during overrun, leading to inefficiencies and potential fluid wastage.
Innovation Solution
A controllable coupling assembly with annular coupling faces and pivotal struts, where forward and reverse struts are biased by springs and engage locking formations to prevent rotation in one direction while allowing freewheeling in the opposite direction, reducing the need for excessive lubrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional one-way clutches use spring-loaded rollers or asymmetric wedges between inner and outer races, then torque transfer and locking function is achieved, but significant lubricating fluid is required to dampen struts during overrun
Solution Approach 1:
The clutch assembly is segmented into multiple functional components: inner race, outer race, struts, locking formations, and control member. This segmentation allows each component to perform its specific function efficiently, reducing the need for excessive lubrication while maintaining reliable torque transfer and locking functions.
Solution Approach 2:
The control member acts as an intermediary that selectively engages or disengages the locking formations based on rotational direction. This intermediary mechanism enables precise control over when locking occurs, allowing the clutch to function reliably with minimal lubricating fluid since the locking formations only engage when needed rather than requiring continuous lubrication during overrun.
2Ease of operation
If excessive lubricating fluid is used to dampen struts during overrun, then smooth operation is maintained, but fluid wastage and inefficiency increase
Solution Approach 1:
The clutch assembly uses dynamic struts that can pivot between engaged and disengaged positions based on rotational direction. During overrun, the struts naturally pivot to their appropriate position without requiring excessive lubrication, as the motion is controlled by the geometry of the pockets and locking formations rather than fluid damping alone.
Solution Approach 2:
The locking formations and pocket geometry are designed to guide the struts into their correct positions automatically during operation. The struts self-regulate their engagement and disengagement based on the rotational direction and the mechanical geometry of the assembly, eliminating the need for excessive lubricating fluid to dampen and control their motion.
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 assembly effectively manages torque transfer and freewheeling without the need for large quantities of lubricating fluid, enhancing efficiency and reducing fluid wastage.
Implementation Method 1
forward and reverse struts are biased by springs and engage locking formations to prevent rotation in one direction while allowing freewheeling in the opposite direction
Data Source
AI summary
An overrunning one-way clutch or coupling assembly includes a first outer coupling member and an inner coupling member which together have a first pair of annular coupling faces therebetween and a second outer coupling member which together with the inner coupling member have a second pair of annular coupling faces therebetween. Both pairs of coupling faces are formed with sets of pockets and locking formations. Forward and reverse sets of struts are located in pockets axially spaced apart from each other.