Overrunning Coupling Locking Member Draft Angle Dynamics
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Solution Overview
Problem
Existing overrunning clutches experience noise issues during the 'overrunning' condition due to strut instability, which affects durability and efficiency, and the laydown speed of struts is not adequately controlled, especially with varying frictional coefficients and material properties.
Innovation Solution
The design incorporates a locking member with a draft angle ranging from 0.0° to 30° to improve laydown speed dynamics and minimize variations caused by frictional coefficients, allowing for either passive or active operation, and includes a cover plate to manage centrifugal forces, enabling strut laydown at lower RPM with reduced oil usage and drag.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the strut mass is reduced to minimize ratcheting noise during overrun, then the noise level decreases, but the strut stability and durability are compromised
Solution Approach 1:
The patent modifies the geometric parameters of the strut, specifically introducing a draft angle (5-30 degrees) on the side surfaces and optimizing the length-to-diameter ratio (2:1 to 5:1). These parameter changes allow the strut to maintain stability during overrun without requiring mass reduction, thereby preventing both noise and instability issues simultaneously
Solution Approach 2:
The patent enables the strut to dynamically adapt its orientation during operation. The drafted side surfaces allow the strut to pivot and lay down at specific angles during overrun conditions, optimizing its position to minimize noise while maintaining stability. The strut transitions between engaged and overrun positions smoothly, reducing harmful vibrations and noise
2Speed
If the strut laydown speed is increased to improve responsiveness during overrun, then the clutch engagement speed improves, but the frictional wear and energy loss increase
Solution Approach 1:
The patent optimizes the strut's geometric parameters, specifically the draft angle (5-30 degrees) and length-to-diameter ratio (2:1 to 5:1), to achieve optimal laydown speed. These parameter changes enable the strut to reach its laydown position quickly during engagement while minimizing frictional contact during overrun, thereby reducing energy loss
Solution Approach 2:
The drafted side surfaces are pre-configured to guide the strut into its optimal laydown position during overrun. This preliminary geometric configuration ensures that when overrun conditions occur, the strut naturally pivots to the correct angle without requiring additional force or energy, minimizing frictional wear and energy loss
3Speed
If the draft angle of the locking member side surface is increased to improve laydown speed dynamics, then the laydown speed control improves, but the manufacturing complexity increases
Solution Approach 1:
The patent specifies an optimal draft angle range (5-30 degrees) that balances performance and manufacturability. This parameter range provides sufficient laydown speed control while remaining compatible with standard manufacturing processes such as CNC machining and mold formation, avoiding excessive manufacturing complexity
Solution Approach 2:
The draft angle is designed to work in conjunction with the strut's rotational motion during clutch operation. The geometric feature is simple enough to manufacture but becomes dynamically effective only during rotation, allowing complex functional behavior to arise from relatively simple manufacturing requirements
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 solution reduces noise and enhances durability by stabilizing the strut laydown process, allowing for efficient torque transfer and reduced operational complexity, with improved manufacturing feasibility and lower energy consumption.
Implementation Method 1
The design incorporates a locking member with a draft angle ranging from 0.0° to 30° to improve laydown speed dynamics and minimize variations caused by frictional coefficients, allowing for either passive or active operation, and includes a cover plate to manage centrifugal forces, enabling strut laydown at lower RPM with reduced oil usage and drag.
Implementation Method 2
The at least one side surface has a draft with a draft angle to improve locking member dynamics with regards to locking member laydown speed and to minimize laydown speed variation caused by a variable frictional coefficient between the pocket surface and the at least one side surface.
Data Source
AI summary
Overrunning coupling and control assembly, coupling assembly and locking member having at least one side surface with a draft to improve locking member dynamics are provided. Locking member dynamics is improved with regards to locking member laydown speed. Laydown speed variation cause by a variable frictional coefficient between a pocket surface of a pocket in which the locking member is received and nominally retained and the at least one side surface of the locking member is minimized as well.