Overrun Mode Coupling Assembly Reducing Spin Loss
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Solution Overview
Problem
One-way clutches in vehicular transmissions experience spin loss or drag torque during overrun conditions, leading to reduced transmission efficiency, particularly due to the engagement of selector plates with spring-biased reverse struts.
Innovation Solution
A controllable or selectable coupling assembly with an overrun mode is designed, featuring first and second coupling members with recesses and locking members, a control element, and a retainer mechanism that allows controlled movement and prevents contact between the control element and the coupling members during overrun, reducing spin losses by isolating locking member force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a selector plate is urged into contact with a notch plate by spring-biased reverse struts, then the coupling assembly can enable engine braking, but spin loss or drag torque increases during overrun conditions
Solution Approach 1:
The control element is made movable between different positions (engaged and disengaged) rather than being fixed, allowing the system to dynamically switch between enabling engine braking and reducing spin loss during overrun conditions
Solution Approach 2:
The coupling assembly is divided into separate functional components (control element, locking members, retainer mechanism) that can operate independently, allowing the control element to be positioned separately from the coupling members to reduce drag torque
2Power
If locking members are engaged with coupling members, then torque transmission is enabled, but drag torque is generated during overrun conditions
Solution Approach 1:
The retainer mechanism acts as an intermediary that applies a retainer force to counterbalance the locking member force, allowing the locking members to be positioned without generating net drag torque on the coupling members during overrun conditions
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 solution effectively reduces spin losses and enhances transmission efficiency by allowing controlled engagement and disengagement of the locking members, thereby minimizing drag torque during overrun conditions.
Implementation Method 1
the retainer mechanism applies a retainer force to the control element to counterbalance the locking member force
Data Source
AI summary
A controllable or selectable coupling assembly having an overrun mode and a retained control element is provided. The assembly includes first and second coupling members having first and second coupling faces, respectively, in close-spaced opposition with one another. A locking member is disposed between the coupling faces of the coupling members. The locking member is movable between first and second positions. A control element is mounted for controlled movement between the coupling faces and is operable to control position of the locking member. The control element has at least one opening which extends completely therethrough to allow the locking member to extend therethrough. A retainer mechanism is operative to allow limited movement of the control element towards the first coupling face and prevent the control element from contacting the first coupling member in the overrun mode thereby reducing spin losses when the assembly is disengaged.