Three-Cylinder Engine Vibration Control via Mount Stiffness and Balance Weight Tuning
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Solution Overview
Problem
Three cylinder engines face challenges in balancing primary couples in the crankshaft axis pitch and yaw directions, leading to unbalanced forces that cause precessional movements and increased engine weight due to heavy weights used for vibration reduction.
Innovation Solution
The engine mounts are configured with different spring constants (K_V > K_H) and a vibration alleviation unit is integrated into the crankshaft system, adjusting the balance weights to ensure 0 < MV/MV0 < 0.5, prioritizing yaw vibration over pitch vibration to reduce vehicle vibrations while minimizing the weight of the alleviation unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If heavy weights are used to balance primary couple in crankshaft axis pitch direction, then vibration is reduced, but engine weight increases
Solution Approach 1:
The patent changes the balance weight ratio parameter (MV/MV0) from the conventional 0.5 to a specific range (0.2-0.4), and adjusts the spring constant ratio (KV/KH) of engine mounts. These parameter changes achieve effective vibration reduction without requiring heavy balance weights, thus resolving the contradiction between vibration reduction and engine weight increase.
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 configuration effectively reduces vehicle vibrations, improves riding comfort, and decreases engine weight, while maintaining engine stability and durability, thereby enhancing fuel efficiency during idling.
Implementation Method 1
K V represents a spring constant of at least one of the engine mounts in a crankshaft axis pitch direction, K H represents a spring constant of the engine mount in a crankshaft axis yaw direction
Data Source
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AI summary
Disclosed is a three cylinder engine wherein a vibration alleviation unit for alleviating vibrations in a vehicle when the engine is mounted in the vehicle is disposed either upon the crankshaft or upon a part that operates in unison with the crankshaft. The three cylinder is supported on the chassis by way of engine mounts that are positioned upon at least both ends of the engine in the direction of the crankshaft axis. Given that KV represents the spring constant of one of the engine mounts in the pitch direction of the crankshaft, KH represents the spring constant of the engine mount in the yaw direction of the crankshaft, MV represents the component of a primary couple that occurs in the three cylinder engine in the pitch direction, MH represents the component of the primary couple that occurs in the three cylinder engine in the yaw direction, and MVO represents the sum of MV and MH, then spring constants of the engine mounts are set such that KV > KH and the vibration alleviation unit is set so as to satisfy the condition 0 < MV/MV0 < 0.5.