Selectable One-Way Clutch Thermal Stopper
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Solution Overview
Problem
Conventional selectable one-way clutches experience unwanted engagement at low temperatures due to increased viscosity of lubrication oil, causing the selector plate to rotate unwillingly and leading to accidental engagement between the pocket and notch plates.
Innovation Solution
Incorporation of a heat-shrinkable stopper member on a plunger that restricts the plunger's motion when thermally shrunk, preventing undesirable engagement by ensuring the plunger cannot be pushed into the actuator, thus maintaining the clutch in a disengaged state at low temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If lubrication oil is applied to friction sites to reduce friction, then friction between the pocket plate and selector plate, and between the selector plate and notch plate is reduced, but at low temperature the increased viscosity of the oil causes the selector plate to rotate unwillingly and may bring the pocket plate into engagement accidentally with the notch plate
Solution Approach 1:
A stopper member is introduced as an intermediary component between the plunger and the actuator. This stopper member physically blocks the plunger's movement path, preventing the plunger from being pushed into the actuator by the drag torque generated by high-viscosity lubrication oil at low temperatures, thereby eliminating unwanted engagement while maintaining the lubrication system
Solution Approach 2:
The invention changes the physical state of the stopper member based on temperature. The stopper member is designed to be thermally expandable, transitioning from a shrunk state (at normal temperatures) where it allows plunger movement, to an expanded state (at low temperatures) where it restricts plunger movement to prevent unwanted engagement caused by high oil viscosity
2Strength
If the viscosity of lubrication oil is high, then the lubrication film is stronger and protects friction surfaces, but the selector plate may be rotated unwillingly by drag torque or shearing force resulting from rotation of the notch plate
Solution Approach 1:
The invention converts the harmful effect of high-viscosity drag torque into a beneficial locking mechanism. The stopper member is designed to be restrained by the very drag torque that would otherwise cause unwanted engagement, transforming the harmful force into a useful locking action that prevents the selector plate from rotating unwillingly
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 unwanted engagement of the selectable one-way clutch at low temperatures by ensuring the plunger is locked in place, even with increased lubrication oil viscosity, thereby maintaining the clutch in the correct operational mode.
Implementation Method 1
the stopper member may be made of heat-shrinkable material in such a manner as to allow the reciprocating motion of the plunger when it is thermally expanded, and to restrict the reciprocating motion of the plunger when it is thermally shrunk
Data Source
AI summary
A selectable one-way clutch is provided. The selectable one-way clutch is shifted between overrunning mode and engagement mode by rotating a selector plate interposed between a notch plate and a pocket plate. The selectable one-way clutch comprises: a plunger that is connected to the selector plate and that is reciprocated by the actuator; a thermally shrinkable stopper member that is fitted onto the plunger; and a stationary member to which the stopper member is brought into abutment by a reciprocating motion of the plunger.