Radially Adjustable Balance Shaft Gear Arrangement for Marine Engine Vibration Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Marine engines face significant secondary vibrational forces due to asymmetrical piston accelerations, leading to undesirable shaking forces that are not effectively balanced by conventional counterweight systems, particularly in larger displacement engines.
Innovation Solution
A balance shaft arrangement is implemented, featuring a drive gear and a driven gear connected to balance shafts with counterweights, where the driven gear is radially positionable to adjust alignment and reduce gear noise, and a dampening member is used to absorb vibrations and torque fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional counterweight systems are used to balance secondary vibrational forces, then the engine structure is simple, but the balancing effectiveness is insufficient particularly in larger displacement engines
Solution Approach 1:
The balance shaft system is segmented into multiple independently adjustable balance shafts (typically two), each capable of being radially positioned relative to the crankshaft. This segmentation allows each balance shaft to be optimized for specific vibration frequencies and directions, improving overall balancing effectiveness without requiring a completely complex integrated system
Solution Approach 2:
The balance shafts are made radially adjustable relative to the crankshaft through movable mounting mechanisms. This dynamic capability allows the balance shafts to be positioned at optimal radial distances from the crankshaft center, enabling effective balancing across different engine operating conditions and displacement sizes while maintaining a relatively simple base structure
2Device complexity
If fixed alignment between drive gear and driven gear is used, then the gear system is simple, but gear noise and vibration transfer are increased
Solution Approach 1:
The driven gear is mounted on the balance shaft in a radially adjustable manner, allowing the center distance and alignment between the drive gear and driven gear to be optimized. This dynamic adjustment capability reduces gear mesh noise and minimizes vibration transfer to the balance shaft system, achieving quieter operation without significantly complicating the gear system through the use of standard adjustable mounting mechanisms
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 balance shaft arrangement effectively reduces secondary vibrational forces and gear noise by allowing adjustable alignment between gears, thereby minimizing the transfer of vibrations and improving the overall balance and operation of marine engines.
Implementation Method 1
a dampening member is disposed between the driven gear and the balance shaft, the dampening member accommodating radial positioning of the driven gear with respect to the balance shaft
Data Source
AI summary
A balance shaft arrangement is for a marine engine having a crankshaft supported for rotation about a crankshaft axis and a drive gear supported for rotation with the crankshaft. The balancing arrangement has at least one balance shaft, and a driven gear being driven into rotation by the drive gear, the driven gear being connected to the balance shaft so as to drive the balance shaft into rotation. The driven gear is selectively radially positionable towards and away from the drive gear. A dampening member is disposed between the driven gear and the balance shaft, the dampening member accommodating radial positioning of the driven gear with respect to the balance shaft.