Engine Belt Pulley Stepped Structure for Abnormal Noise Blocking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The mild hybrid vehicle structure with a 48V battery system experiences increased belt load and torsional vibration, leading to belt durability issues, slip, and abnormal noise due to interference between the belt pulley and torsional vibration damper, which existing solutions like pulley decouplers only partially address while introducing Noise-Vibration-Harshness (NVH) issues.
Innovation Solution
A stepped portion is formed in the radial direction of the belt pulley structure to block sound waves generated between the belt pulley and torsional vibration damper, preventing them from radiating outside and altering the resonance characteristics to eliminate abnormal noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pulley decoupler is mounted on the belt pulley to stabilize vibration, then belt durability is improved, but Noise-Vibration-Harshness (NVH) increases due to interference between structures
Solution Approach 1:
The patent extracts and isolates the noise-generating cavity between the belt pulley and torsional vibration damper by introducing a stepped portion. This separates the harmful sound waves from the functional vibration damping, allowing the decoupler to maintain belt durability while the stepped portion prevents noise radiation.
Solution Approach 2:
The stepped portion acts as an intermediary structure between the belt pulley and torsional vibration damper. It introduces a blocking feature that mediates the interaction between these components, preventing sound wave transmission while allowing the vibration damping function to continue operating effectively.
2Stability of the object's composition
If a torsional vibration damper is installed on the belt pulley to reduce torsional vibration, then engine vibration is reduced, but abnormal noise is amplified in specific frequency bands
Solution Approach 1:
The stepped portion is introduced locally at the interface between the belt pulley and torsional vibration damper. This localized modification affects only the specific frequency band where noise is generated, while preserving the overall vibration damping function across other frequency ranges.
Solution Approach 2:
The stepped portion is designed in advance to block sound waves before they can be amplified by the torsional vibration damper. By preventing sound wave transmission at the source, the structure eliminates abnormal noise in specific frequency bands while maintaining the vibration reduction function.
3Device complexity
If the cavity between belt pulley and torsional vibration damper is left open, then structural simplicity is maintained, but sound waves are diverted to the outside causing abnormal noise
Solution Approach 1:
The stepped portion segments the cavity space radially, creating a blocked configuration that prevents sound wave transmission. This segmentation approach adds minimal structural complexity while effectively isolating the noise source from the external environment.
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 prevents abnormal noise generation by blocking sound waves within the cavity, enhancing the durability and noise reduction in the engine structure without introducing additional NVH issues.
Implementation Method 1
a stepped portion may be formed in a shape of blocking, in a radial direction, a cavity disposed at a portion where a belt pulley and a torsional vibration damper face each other
Implementation Method 2
which changes the resonance characteristic in the belt pulley structure, thereby preventing abnormal noise from being generated in the engine structure
Data Source
AI summary
A belt pulley structure of an engine is provided to prevent abnormal noise from generating between a belt pulley and a torsional vibration damper. The belt pulley structure includes a stepped portion that is formed in a shape that blocks a cavity in a radial direction thereof. The cavity is formed at a portion where a belt pulley and a torsional vibration damper face each other.