Isolating Decoupler with One-Way Clutch for Crankshaft Vibration
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Solution Overview
Problem
Crankshaft isolators with no decoupling feature face challenges during engine start-up and shutdown due to excessive deformation and potential fatigue fractures, as the spring stiffness causes the engine RPM to pass through the natural frequency, leading to exaggerated relative motion and noise issues, which existing solutions attempt to mitigate with stops but result in objectionable noise.
Innovation Solution
An isolating decoupler with a one-way clutch and an inertia member attached to the hub, all contained within a pulley width, utilizing a spring and elastomeric member to absorb vibrations and allow high inertia components to overrun the crankshaft during rapid deceleration, thereby preventing excessive loads on the crankshaft and belt drive system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If spring stiffness is increased to attenuate torsional vibration during engine operation, then vibration attenuation is improved, but excessive deformation and fatigue fracture risk occur during start-up and shut down
Solution Approach 1:
The patent applies a one-way clutch mechanism that allows the pulley to rotate freely in the direction of engine operation while preventing reverse rotation. This dynamic feature enables the system to adapt to different operating conditions: during normal operation, the spring provides vibration attenuation; during start-up and shut down, the one-way clutch prevents excessive reverse motion that would cause fatigue fractures.
Solution Approach 2:
The one-way clutch acts as an intermediary element between the spring and the pulley hub. It mediates the interaction by allowing torque transmission in the forward direction while blocking reverse torque, thereby protecting the spring from excessive deformation during transient conditions while maintaining vibration attenuation during steady operation.
2Reliability
If stops are added to limit elastic element travel and prevent fatigue fractures, then reliability is improved, but objectionable noise occurs during start-up phase
Solution Approach 1:
The one-way clutch serves as an intermediary that prevents the need for physical stops. By allowing free rotation in the forward direction and blocking reverse rotation, it limits elastic element travel without creating the mechanical impact and noise associated with stop-based solutions.
Solution Approach 2:
The patent replaces the mechanical stop system with a one-way clutch mechanism. Instead of using physical barriers that create impact noise, the one-way clutch uses friction and engagement surfaces to smoothly limit reverse motion, eliminating the objectionable noise while maintaining reliability.
3Reliability
If one-way clutch and inertia member are both included, then vibration damping and overload protection are improved, but device complexity increases
Solution Approach 1:
The patent merges the one-way clutch and inertia member into a single integrated assembly where the inertia member is positioned within the pulley and connected to the clutch mechanism. This combination provides both vibration damping and overload protection functions while occupying minimal space and reducing the number of separate components compared to traditional designs.
Solution Approach 2:
The inertia member is nested within the pulley structure, and the one-way clutch is integrated into the same assembly. This nested arrangement allows both components to coexist in a compact configuration, providing enhanced functionality without proportionally increasing device complexity or overall dimensions.
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 dampens crankshaft torsional vibrations, prevents fatigue fractures, and reduces noise during engine operation by allowing high inertia components to temporarily overrun the crankshaft, ensuring reliable operation in confined spaces.
Implementation Method 1
a spring operationally engaged between the one-way clutch and the pulley
Implementation Method 2
effectively dampens crankshaft torsional vibrations
Implementation Method 3
an inertia member engaged with the hub through an elastomeric member
Implementation Method 4
a one-way clutch engaged with the hub
Implementation Method 5
an inertia member engaged with the hub through an elastomeric member, the inertia member moveable independently of the pulley
Data Source
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AI summary
An isolating decoupler comprising a hub, a one-way clutch engaged with the hub, a pulley rotationally engaged with ' the hub, a spring operationally engaged between the one-way clutch and the pulley, and an inertia member engaged with the hub.through an elastomeric member, the inertia member substantially disposed within a width of the pulley, the inertia member moveable independently of the pulley.