Cylindrical Vibration Isolator Mounting Step Boundary
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Solution Overview
Problem
Conventional sub-frame mounts experience a rapid rise in press fitting load during installation, which can damage the rubber seal or cause cracks in the welded portion of the sub-frame, due to the sudden increase in contact area between the large diameter portion and the mounting hole.
Innovation Solution
A cylindrical vibration isolating device with an outer cylinder featuring a small and large diameter portion on its lateral wall, where the boundary between these portions is designed to gradually increase in height axially, allowing a progressive increase in contact area with the mounting hole, thereby smoothing the press fitting load. This design includes a boundary portion shaped like a mountain, with alternating top and bottom sections, an axially extending cavity, and a solid connecting leg in the vibration isolating rubber, along with stoppers to manage torsion and spring rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a large diameter portion is formed on the outer cylinder for press-fitting into the mounting hole, then the mounting strength is improved, but the press fitting load rises rapidly causing damage to the rubber seal or cracks in the welded portion
Solution Approach 1:
The boundary portion between the small diameter portion and large diameter portion is segmented into multiple levels (first level, second level, third level) at different heights in the axial direction. This segmentation allows the contact area to increase progressively rather than all at once, distributing the press fitting load over time and preventing sudden load spikes that would damage the rubber seal or cause cracks.
Solution Approach 2:
The multi-level boundary portion structure performs preliminary action by creating staged contact points before full contact is achieved. As the outer cylinder is pressed into the mounting hole, the first level contacts first, then the second level, and finally the third level, preparing the mounting structure to gradually accommodate the large diameter portion without sudden load increases.
2Object-affected harmful factors
If the boundary portion is changed in height to gradually increase contact area, then the press fitting load is smoothed, but the device structure becomes more complex
Solution Approach 1:
The complexity is localized only to the boundary portion between the small and large diameter portions, while the rest of the outer cylinder maintains a simple cylindrical structure. The multi-level boundary portion is confined to a specific axial region, allowing the majority of the device to remain simple and easy to manufacture while still achieving the load-smoothing effect where needed.
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 gradual increase in press fitting load prevents damage to the rubber seal and welded portions, ensuring a smoother installation process and improved durability by distributing the load effectively and controlling torsional forces.
Implementation Method 1
an inner cylinder and an outer cylinder which are connected through a vibration isolating rubber
Implementation Method 2
cylindrical vibration isolating device
Data Source
AI summary
A cylindrical vibration isolating device that prevents damage to a vibration isolating rubber and cracks in a welded portion of a sub-frame. The sub-frame mount comprises an outer cylinder, an inner cylinder connected by the vibration isolating rubber. Small and large diameter portions are provided on a lateral wall of a barrel portion of the outer cylinder. Between the small and large diameter portions is formed a step-like boundary portion. The height in the axial direction of the boundary portion changes in the circumferential direction and has a substantially mountain-like shape with a top projecting in the press fitting direction. A contact area of the large diameter portion contacting a mounting hole of the sub-frame is increased in accordance with an amount of the press fitting. Therefore, when the sub-frame mount is press-fitted into the mounting hole of the sub-frame, the press fitting load is gradually increased.