Selectable One-Way Clutch Drag Torque Control
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Solution Overview
Problem
Conventional selectable one-way clutches experience undesirable rotation of the selector plate due to drag torque from lubrication oil, especially at low temperatures, leading to accidental engagement between the pocket and notch plates.
Innovation Solution
Incorporation of a drag increasing device with teeth or protrusions and depressions between the pocket and selector plates to enhance drag resistance, ensuring the selector plate remains stable against unwanted rotation while allowing controlled engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lubrication oil with high viscosity is applied to reduce friction between the pocket plate, selector plate, and notch plate, then friction is reduced, but the selector plate may be rotated undesirably by drag torque when the pocket plate is halted
Solution Approach 1:
A drag increasing device is introduced as an intermediary element between the pocket plate and selector plate. This device increases the drag force that opposes unwanted rotation of the selector plate, thereby preventing accidental engagement while still allowing controlled rotation by the actuator when needed.
Solution Approach 2:
The drag increasing device changes the drag parameter between the pocket plate and selector plate. By increasing the drag force in the circumferential direction, the system prevents the selector plate from rotating undesirably due to drag torque from the lubrication oil, while maintaining the ability to rotate when actuated.
2Reliability
If lubrication oil is applied between the pocket plate and notch plate, then friction is reduced, but the selector plate may be brought into engagement accidentally with the notch plate at extremely low temperatures
Solution Approach 1:
The drag increasing device serves as an intermediary that provides temperature-compensated drag control. It ensures that even at extremely low temperatures where lubrication oil viscosity increases and causes excessive drag torque, the selector plate remains stable and does not engage accidentally with the notch plate.
3Reliability
If the drag between the pocket plate and selector plate is increased to prevent unwanted rotation, then engagement stability is improved, but the actuator may have difficulty rotating the selector plate
Solution Approach 1:
The drag increasing device is designed with local quality - it provides increased drag in the circumferential direction to prevent unwanted rotation, while maintaining ease of rotation in the axial direction when actuated. This directional selectivity ensures stability during normal operation while allowing actuator-driven engagement when needed.
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
Prevents undesirable rotation of the selector plate due to increased drag, ensuring reliable torque transmission in the intended direction without interfering with actuator-driven engagement.
Implementation Method 1
a drag increasing device that increases a drag acting between the pocket plate and the selector plate
Implementation Method 2
lubrication oil is applied to the selectable one-way clutch to form oil films in friction sites between the pocket plate and the selector plate, and between the selector plate and the notch plate
Implementation Method 3
a drag torque or a shearing force resulting from a rotation of the notch plate
Data Source
AI summary
A selectable one-way clutch adapted to prevent an undesirable engagement is provided. The selectable one-way clutch comprises a drag increasing device that increases a drag of oil acting between the pocket plate and the selector plate against a force rotating the selector plate in a direction to bring the selectable one-way clutch into the engagement mode.