Teeter-Totter Strut Geometry for Shock-Resistant Clutch Locking
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Solution Overview
Problem
Unintended deployment of locking members in clutch assemblies due to shock loads can cause undesirable operation and damage, particularly when solenoid springs fail, leading to unintended engagement of struts.
Innovation Solution
A clutch assembly with a teeter-totter strut design that includes geometric enhancements such as positioning the center of mass behind the pivot point and altering pocket geometry to prevent unintended deployment, utilizing a normally off actuator and return spring configuration to maintain the strut in a disengaged position during shock loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solenoid spring fails or a strut spring fails, then the plunger or strut becomes free to move, but this results in unintended deployment of the strut during shock loads
Solution Approach 1:
The patent applies preliminary anti-action by designing the strut geometry and pocket configuration to preemptively counteract shock load forces. The center of mass is positioned behind the pivot point, creating a negative moment that opposes any unintended engagement motion before it can occur. This preventive design ensures that even if spring forces fail, the strut geometry itself resists shock-induced deployment.
Solution Approach 2:
The patent employs asymmetry in the strut design, specifically positioning the center of mass behind the pivot point rather than at the geometric center. This asymmetric mass distribution creates a stabilizing negative moment during shock loads, preventing the strut from rotating into engagement. The asymmetric pocket geometry also contributes to this effect by providing unequal constraints on either side of the pivot point.
2Speed
If the teeter-totter strut is designed to pivot freely to engage during shock load, then response time is improved, but unintended deployment occurs causing damage
Solution Approach 1:
The patent changes the physical parameters of the strut system, specifically the center of mass position and moment of inertia, to alter the dynamic response characteristics. By positioning the center of mass behind the pivot point, the system achieves a negative moment that prevents unintended engagement while still allowing controlled engagement when actuated. This parameter modification enables the strut to respond quickly to legitimate engagement signals while resisting false activation from shock loads.
3Strength
If the engagement face extends out from the pocket, then locking capability is achieved, but the strut becomes vulnerable to shock load forces
Solution Approach 1:
The patent applies the counterweight principle by positioning the center of mass behind the pivot point, creating a counterbalancing moment that opposes shock load forces acting on the engagement face. This counterweight effect generates a negative moment that stabilizes the strut in the disengaged position during shock events, preventing unintended deployment while maintaining full locking capability when engaged through normal actuation.
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 enhanced teeter-totter strut design effectively prevents unintended deployment by creating a negative moment about the pivot point, reducing the risk of strut engagement and potential damage, thereby enhancing the reliability and safety of clutch assemblies under shock load conditions.
Implementation Method 1
The enhanced teeter-totter strut design effectively prevents unintended deployment by creating a negative moment about the pivot point
Data Source
AI summary
A clutch assembly includes a pocket plate having a pocket and a teeter-totter strut retained in the pocket. The teeter-totter strut is pivotable to an engaged position in which an engagement face of the teeter-totter strut extends out from the pocket plate. The teeter-totter strut is pivotable from the engaged position to a disengaged position in which the engagement face of the teeter-totter strut does not extend out from the pocket plate. The clutch assembly is configured so that when a shock load force acts on the teeter-totter strut, the teeter-totter strut is prevented from moving into the engaged position.