Selectively Controlled Rocker One-Way Clutch Backlash Reduction
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Solution Overview
Problem
Conventional one-way clutches face limitations in torque capacity, space efficiency, noise due to excessive internal backlash, and require significant machining, making them costly and complex, especially when formed from powder metal for applications like automatic transmissions.
Innovation Solution
An overrunning clutch assembly with a ring and rocker design featuring pockets, springs, and notches, where rockers pivot to engage or disengage with notches, and an actuator controls the engagement to minimize backlash and eliminate secondary machining, allowing for easy assembly and reduced noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional one-way clutches use sprags or rollers to connect races, then the clutch can transmit torque in one direction, but the torque transmitting capacity is limited by contact or bearing stresses
Solution Approach 1:
The clutch is divided into multiple independent rockers (typically 3-6) distributed around the circumference, each engaging with notches on the races. This segmentation distributes the torque load across multiple contact points, reducing the stress on each individual rocker while maintaining high overall torque capacity.
Solution Approach 2:
The design transitions from point contact (sprags/rollers) to line contact through the rocker-notch interface. The rockers engage with notches that extend radially, creating a larger contact area and distributing stresses over a broader region, thereby increasing torque capacity without proportionally increasing contact stresses.
2Strength
If conventional one-way clutches are formed from bearing grade steel, then the races can withstand operating hoop stress, but the manufacturing cost and complexity increase
Solution Approach 1:
The design modifies the stress distribution parameters by introducing rockers with specific geometric profiles and notch configurations. This changes how loads are transmitted through the races, reducing peak hoop stresses to levels that allow the use of cost-effective sintered powder metal instead of expensive bearing grade steel.
Solution Approach 2:
The clutch employs a composite construction where sintered powder metal races are used in conjunction with properly designed rocker components. The sintered metal provides adequate strength at reduced cost, while the rockers (which can be formed from various materials including powder metal) handle the dynamic loading, creating an optimized material system.
3Ease of manufacture
If sintered powder metal is used to form clutch components, then production cost is reduced, but excessive internal backlash produces noise at unacceptable levels
Solution Approach 1:
The rockers are designed with pre-loaded springs that apply a constant force to maintain engagement between the rockers and notches. This preliminary action eliminates backlash by ensuring continuous contact pressure, preventing the excessive clearance that would otherwise cause noise in sintered metal components.
Solution Approach 2:
The design adjusts geometric parameters including rocker length, notch depth, and spring pre-load forces to optimize engagement characteristics. These parameter changes ensure that sintered metal components maintain tight tolerances and minimal backlash during operation, eliminating noise while preserving the cost advantages of powder metal manufacturing.
4Manufacturing precision
If conventional one-way clutches require significant machining of powder metal components, then precise tolerances can be achieved, but manufacturing time and cost increase
Solution Approach 1:
The sintered powder metal components are designed to achieve functional tolerances through the sintering process itself, without requiring extensive secondary machining. The rockers and notches are formed with adequate precision during sintering, and the self-adjusting engagement mechanism compensates for minor variations, eliminating the need for time-consuming machining operations.
Solution Approach 2:
The design modifies tolerance requirements by incorporating compliance elements and self-adjusting features that accommodate larger tolerances. This allows sintered components to be produced with coarser tolerances at higher productivity, while the rock器-notch engagement mechanism maintains proper function and minimizes backlash without requiring tight machining tolerances.
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 design enhances torque capacity, reduces noise, and simplifies assembly by minimizing machining, making it suitable for low-cost, reliable operation in space-constrained applications like automatic transmissions.
Implementation Method 1
springs, each urging a rocker to pivot in a respective pocket
Data Source
AI summary
An overrunning clutch assembly includes a first ring having pockets spaced mutually about an axis, rockers each located in a pocket, springs each urging a rocker to pivot in a respective pocket, and first notches arranged around the axis. A second ring includes second pockets spaced mutually about the axis, second rockers each located in a second pocket such that at least one second rocker is engageable with a notch, second springs each urging a second rocker toward engagement with a notch, and second notches around the axis, at least one rocker being engageable with at least one second notch. A control member moves about the axis alternately to prevent the first rockers from engaging the second notches and to permit the first rockers to engage the second notches.