Flexure Engine Mount With Directional Stiffness for Vibration Isolation
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Solution Overview
Problem
Conventional compliant engine mounts struggle to effectively reduce vibration and force transmission between engines and vehicle structures while minimizing excessive deflections and deformations, due to the limitations of elastomeric materials which exhibit 'set' and 'creep' over time, requiring additional design compromises.
Innovation Solution
The engine mount device incorporates a housing and carrier with a flexure that provides higher stiffness in radial directions compared to axial directions, utilizing a trunnion pin and elastomeric material to isolate vibrations and allow for axial movement, while snubbing surfaces prevent excessive deflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If elastomeric materials are used in conventional compliant mounts to reduce vibration and force transmission, then vibration isolation is improved, but the mount exhibits compression set and creep over time requiring additional design compromises
Solution Approach 1:
The patent changes the material parameters by transitioning from elastomeric materials to spring steel, fundamentally altering the mechanical properties. Spring steel provides consistent elastic behavior without compression set or creep, maintaining both vibration isolation and dimensional stability over time.
Solution Approach 2:
The invention uses a composite structure combining spring steel flexures with elastomeric damping elements. The spring steel provides structural integrity and elastic recovery, while the elastomers provide vibration damping, achieving both reliability and material stability.
2Reliability
If conventional compliant mounting systems are designed to reduce vibration transmission, then vibration isolation is improved, but static displacement of the supported structure increases
Solution Approach 1:
The patent applies different stiffness characteristics to different directions: the spring steel flexures provide high radial stiffness to limit static displacement while maintaining low axial stiffness for vibration isolation. This directional differentiation resolves the contradiction between vibration reduction and displacement control.
Solution Approach 2:
The spring steel flexures provide dynamic elastic behavior that adapts to loading conditions, maintaining optimal stiffness characteristics during vibration cycles while limiting static displacement through controlled elastic deformation.
3Ease of operation
If stops are incorporated in conjunction with elastomers to minimize excessive deflections, then motion control is improved, but the stops must be designed to accommodate set and creep throughout operational life
Solution Approach 1:
The patent extracts the stops from the design entirely by using spring steel flexures that provide inherent elastic recovery and controlled motion limits without requiring separate snubbing elements. This eliminates the complexity of designing stops that accommodate material degradation.
Solution Approach 2:
The spring steel flexures are self-regulating, providing both motion control and vibration isolation without requiring additional components. The material's inherent elastic properties automatically limit deflections while maintaining 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
This configuration significantly reduces vibration transmission and deflections, maintaining effective vibration isolation and motion control over the engine mount's lifespan by enhancing radial stiffness and controlling axial movement.
Implementation Method 1
at least one flexure connecting the carrier to the housing. The at least one flexure is configured to provide higher stiffness in one or more radial directions of the hole compared to a stiffness provided in an axial direction of the hole
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
An engine mount device includes a housing; a carrier that is at least partially inside the housing, the carrier comprising a hole through at least a partial thickness of the carrier, the hole being configured to receive a trunnion pin; and at least one flexure connecting the carrier (140, 220) to the housing. The at least one flexure is configured to provide higher stiffness in one or more radial directions of the hole compared to a stiffness provided in an axial direction of the hole. The housing and/or the carrier comprise one or more snubbing surfaces configured to limit a deflection of the carrier relative to the housing.