Filtering Pulley With Segmented Elastic Assemblies
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Solution Overview
Problem
Existing filtering pulleys for internal combustion engine crankshafts face a challenge in effectively filtering torsional vibrations while maintaining sufficient rigidity to handle high loads, as the elastic elements' rigidity must be low to filter oscillations but cannot be reduced further due to high loads.
Innovation Solution
A filtering pulley design featuring a hub connected to a shaft, an annular pulley ring with a dynamic damper and friction damper, and arched elastic assemblies with varying rigidities, allowing for a high free angle to decouple the hub and pulley ring during high amplitude oscillations and asymmetric damping behavior to manage torsional vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the rigidity of the elastic elements is lowered to filter torsional oscillations, then the filtering capability is improved, but the ability to handle high loads deteriorates
Solution Approach 1:
The elastic element is segmented into multiple discrete springs arranged circumferentially around the pulley ring. This segmentation allows each spring to independently deform and absorb torsional oscillations, while the collective arrangement of multiple springs maintains sufficient load handling capability. The segmentation enables the system to achieve both filtering and strength requirements through distributed elastic elements.
Solution Approach 2:
The elastic element uses a composite structure combining multiple spring materials with different rigidity characteristics. By selecting appropriate materials and configurations for each spring, the system achieves a balance between low equivalent rigidity for oscillation filtering and sufficient load bearing capacity. The composite approach allows optimization of both contradictory requirements through material and structural diversity.
2Object-affected harmful factors
If the rigidity of the elastic elements is lowered to filter oscillations, then the oscillation filtering is improved, but the torque transmission capability deteriorates
Solution Approach 1:
The segmentation of the elastic element into multiple circumferentially arranged springs allows the system to filter oscillations through individual spring deformation while maintaining torque transmission through the collective action of all springs. Each spring contributes to both oscillation damping and torque transmission, resolving the contradiction between filtering and power transmission.
Solution Approach 2:
The elastic element is designed with dynamic characteristics that allow it to adapt its rigidity based on operating conditions. During oscillations, the springs deform to provide damping, while during torque transmission, the springs engage to transfer power. This dynamic behavior enables the system to fulfill both filtering and torque transmission functions without compromising either.
3Object-affected harmful factors
If a filtering pulley is used to filter torsional vibrations, then the belt is protected from periodic tension variations, but the device complexity increases
Solution Approach 1:
The elastic element serves multiple functions simultaneously: it acts as a spring for oscillation filtering, as a damper for vibration reduction, and as a torque transmitting element. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity while achieving effective protection of the belt from periodic tension variations.
Solution Approach 2:
The filtering function is merged with the torque transmission function within a single integrated elastic element structure. The multiple springs are combined into one assembly that performs both oscillation filtering and power transmission, avoiding the need for separate filtering and transmission mechanisms, thus controlling device complexity.
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 design achieves effective filtering of torsional oscillations with high rigidity for torque transmission and optimal damping, reducing impact on the belt and ancillaries, particularly during start-up, while maintaining low equivalent rigidity to manage high loads.
Implementation Method 1
one or more elastic assemblies (40) arranged circumferentially in the chamber (15), each comprising a pair of helical springs (41, 42) positioned in series with each other
Implementation Method 2
a friction damper (27) radially interposed between the inner cylindrical wall (8) and the hub portion (22) of the disc (21)
Implementation Method 3
a dynamic damper (19) comprising a disc (21), facing the closing element (11) and having a hub portion (22) integral with the hub (2), and a seismic ring (23) secured to a perimeter flange (24) of the disc (21)
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A filtering pulley (1) comprising a hub (2) adapted to be fixed to a rotating shaft, a pulley ring (3) mounted coaxial and rotationally free on the hub (2), a plurality of elastic assemblies (40) arranged circumferentially with respect to the hub (2) and the pulley ring (3) and each interposed between a pair of first elements (50) integral with the hub (2) and between a pair of second elements (16, 17) integral with the pulley ring (3), in which each elastic element forms with the first elements (50) and with the second elements (16, 17) respective angular clearances (σ, a), the pulley ring (3) and the hub (2) having a free angle (β) of relative rotation equal to the sum of the above-mentioned angular clearances (σ, α).