Engine Mounting Legs with Differential Stiffness for Vibration Isolation
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Solution Overview
Problem
Internal combustion engines generate vibrations that adversely impact vehicles such as unmanned aerial vehicles and radio-controlled model aircraft, necessitating effective vibration isolation to minimize these vibrations in all six degrees of freedom.
Innovation Solution
A compliant engine mounting system is integrated directly to the engine crankcase, featuring mounting legs with crankcase arms and vibration damping subassemblies, allowing for differential stiffness and orientation to isolate engine vibrations from the vehicle frame, thereby reducing torsional impulse forces and facilitating easy installation and maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid engine mounting system is used, then structural strength is improved, but vibration isolation deteriorates
Solution Approach 1:
The mounting system is divided into multiple independent mounting legs (typically three or more) that are spaced around the engine crankcase. Each leg acts as an independent vibration isolation element, allowing the system to maintain overall structural strength while providing distributed vibration damping throughout the mounting structure.
Solution Approach 2:
The mounting legs incorporate vibration damping elements with specific material properties and geometric configurations that provide optimal balance between stiffness and damping. The legs may include features such as elastomeric materials, tuned mass dampers, or compliant joints that change the dynamic characteristics of the mounting system to isolate vibrations while maintaining structural integrity.
2Object-affected harmful factors
If multiple mounting legs with different configurations are used, then vibration isolation is improved, but device complexity increases
Solution Approach 1:
The mounting legs are configured with different orientations and potentially different damping characteristics to address the six degrees of freedom of vibration. The legs are positioned asymmetrically around the engine crankcase with specific angular spacing (e.g., 120 degrees apart for three legs) to optimize vibration isolation in all directions while maintaining a relatively simple overall structure.
Solution Approach 2:
Each mounting leg is designed to perform multiple functions: structural support, vibration damping, and angular adjustment. The legs may incorporate universal joints or compliant mechanisms that allow them to accommodate engine movements and vibrations while maintaining proper mounting geometry, reducing the need for additional specialized components.
3Ease of operation
If the engine mounting system is integrated directly to the crankcase, then ease of installation is improved, but manufacturing precision requirements increase
Solution Approach 1:
The mounting legs are integrally formed with or directly attached to the engine crankcase as a unified assembly, eliminating the need for separate mounting brackets or additional fastening hardware. This integration simplifies installation to a single mounting operation while incorporating built-in alignment features and tolerance compensation mechanisms that reduce the impact of manufacturing variations.
Solution Approach 2:
The mounting system incorporates self-aligning features such as spherical joints, conical mounting surfaces, or compliant elements that automatically compensate for minor misalignments and manufacturing tolerances during installation. This self-adjusting capability reduces the precision requirements for crankcase mounting surfaces while ensuring proper alignment and vibration isolation performance.
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 decouples engine vibrations from the vehicle, minimizing torsional vibrations and reducing the number of assembly parts required, ensuring stable operation and ease of installation, particularly beneficial for UAV applications.
Implementation Method 1
vibration damping subassemblies, allowing for differential stiffness and orientation to isolate engine vibrations from the vehicle frame
Implementation Method 2
A compliant engine mounting system is integrated directly to the engine crankcase, featuring mounting legs with crankcase arms and vibration damping subassemblies
Data Source
AI summary
An engine assembly having an improved mounting system or assembly is disclosed. Features of this mounting system include having crankcase arms that are integrally formed with a crankcase of the engine assembly, having multiple mounting legs that each have a dedicated vibration damping subassembly and where the stiffness of at least two of the mounting legs is different (by varying the configurations of the corresponding vibration damping subassemblies), and using a mounting ring or base with having differently oriented mounting pads for securement of the corresponding mounting leg relative thereto.