Power Transmission Pulley With Freewheel And Resilient Element
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Solution Overview
Problem
Existing power transmission pulleys, such as freewheel and resilient pulleys, face issues like rigid mechanical contact leading to dynamic forces and internal friction, which result in damage, slip, fatigue, and wear, especially when dealing with accessories like alternators that experience velocity fluctuations and opposing torque.
Innovation Solution
A power transmission pulley design that combines a freewheel mechanism with a resilient element, where the radial load is supported by a ball bearing centered relative to the belt, and the mechanical connection is established via the resilient element only when the freewheel is locked, allowing the driven member to continue rotating freely during deceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a freewheel mechanism with rigid mechanical contact is used, then decoupling function is provided, but dynamic forces and impacts are generated causing damage, slip, fatigue and wear
Solution Approach 1:
A resilient element is introduced as an intermediary between the freewheel mechanism and the driven accessory. This resilient element absorbs and dampens the dynamic forces and impacts generated by the rigid mechanical contact of the freewheel, thereby reducing harmful effects such as belt slip, bearing fatigue, and component wear while maintaining the decoupling function.
Solution Approach 2:
The resilient element is positioned to cushion the mechanical contact before the dynamic forces can propagate through the system. By placing the damping element in advance of the harmful force transmission path, the system prevents rather than merely reacts to the damaging effects of rigid coupling.
2Power
If the driven member has high opposing torque, then power transmission is maintained, but the deceleration follows the driving portion motion closely transmitting dynamic forces in full
Solution Approach 1:
The resilient element acts as a mediator between the driven member with high opposing torque and the driving portion. It allows the driven member to maintain power transmission while independently managing its deceleration, preventing the close coupling that would otherwise transmit full dynamic acceleration and deceleration forces through the system.
3Speed
If the velocity fluctuation frequency is close to the resonant frequency of the resilient pulley, then the system operates, but the resilient pulley amplifies the fluctuation leading to high deformation and heating
Solution Approach 1:
The freewheel mechanism serves as an intermediary that decouples the driven accessory from the driving portion during velocity fluctuations. By allowing the driven member to rotate independently when the freewheel is in over-running mode, the system avoids resonant amplification that would otherwise occur through the resilient element, preventing excessive deformation and heating.
Solution Approach 2:
The system transitions between coupled and decoupled states dynamically based on operating conditions. When velocity fluctuations approach resonant frequencies, the freewheel mechanism enables decoupling, allowing the driven member to maintain its own rotational speed independent of the driving portion, thereby avoiding the resonant amplification that would damage the resilient element.
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
This design reduces dynamic forces, minimizes internal friction, and increases the durability of the pulley by limiting resonance amplification and deformation, thereby reducing fatigue and wear, while maintaining effective decoupling even under opposing torque conditions.
Implementation Method 1
The radial load is supported by a ball bearing that is generally centered relative to the belt
Implementation Method 2
a resilient element interposed between the pulley element and a receiver device for coupling to a member driven by the belt
Implementation Method 3
During the decoupling stages that occur in the event of the outer portion decelerating quickly, the inner portion driven by pure inertia maintains a high velocity
Data Source
AI summary
The invention relates to a power transmission pulley comprising a pulley element having a ribbed outer outline that is adapted to receive a ribbed belt, and a resilient element interposed between the pulley element and a receiver device for coupling to a member driven by the belt. The pulley includes a freewheel device disposed in series with the resilient element between the pulley element and said receiver element.