Variable-Stiffness Spherical Hinge With Annular Gap Sealing
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Solution Overview
Problem
Existing spherical hinge products face challenges in achieving variable stiffness that meets the requirement of small stiffness under small loads and significantly increased stiffness under large loads, while also preventing buckling deformation and external contamination, which limits their fatigue life and reliability.
Innovation Solution
A variable stiffness spherical hinge design featuring an annular sealed space with an annular stop, where the annular gap's minimum radial width is adjustable, allowing for linear and nonlinear stiffness adjustments by varying the size and shape of the annular sealed space and stop, preventing buckling, and sealing out dust and debris.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If rubber full through holes are used to meet large variable stiffness requirements, then stiffness can be adjusted, but the product is greatly deformed under load and causes serious buckling phenomenon at the intersection of rubber profiles
Solution Approach 1:
The rubber layer is segmented into multiple independent rubber profiles (first rubber profile, second rubber profile, third rubber profile) arranged in sequence along the radial direction. This segmentation prevents the buckling phenomenon that occurs in fully-through hollow structures by creating discrete load-bearing elements that maintain structural stability under compression and load.
2Reliability
If pre-compression amount is increased to prevent rubber tensile damage, then reliability improves, but the buckling phenomenon becomes more serious and rubber is easy to be in stretched state
Solution Approach 1:
The metal sleeve features localized structural features including a first convex portion and a second convex portion that correspond to the rubber profiles. These localized structural elements provide targeted support at critical locations, allowing the rubber to maintain compression without excessive buckling while preventing tensile damage. The metal core's geometry is optimized locally to match the rubber profile distribution.
3Adaptability or versatility
If structure with external holes is used for stiffness adjustment, then variable stiffness is achieved, but external dust, dirt and sand particles enter the spherical hinges causing corrosion and splitting
Solution Approach 1:
The rubber layer acts as a flexible sealing shell that completely encloses the hollow space, preventing external dust, dirt, and sand particles from entering the internal structure. The rubber profiles maintain compression and seal the hollow space effectively, eliminating contamination issues while preserving variable stiffness functionality through the multi-profile configuration.
4Stability of the object's composition
If pre-compression amount is limited to avoid buckling, then structural stability is maintained, but rubber is easy to be in stretched state and fatigue performance is poor
Solution Approach 1:
The spherical hinge employs a composite structure combining metal components (mandrel, metal sleeve, metal core) with rubber material. The metal components provide structural stability and compression support, while the rubber layer provides elasticity, damping, and sealing. This composite design allows the rubber to remain in a compressed state without excessive stretching, improving fatigue performance while maintaining structural stability.
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 design effectively manages radial deformation, increases pre-compression amounts, enhances fatigue life, and ensures reliable stiffness variation under different loads, while maintaining cleanliness and structural integrity.
Implementation Method 1
an annular gap 12 is formed between the spherical hinge main body 1 and the annular stop 3 along axial direction, and the minimum radial width of the annular gap 12 is X... when the load is small, the volume of the annular gap 12 is gradually reduced, and the stiffness is linearly increased
Implementation Method 2
The pre-compression amount of the product is designed according to the maximum deformation amount of the product during use, so that the occurrence of rubber tensile damage can be effectively avoided
Implementation Method 3
a spherical hinge main body comprising a mandrel, a rubber layer and an inner layer sleeve which are vulcanized and bonded in sequence from inside to outside
Data Source
Figure 1~2
Figure 3~4
AI summary
A variable stiffness spherical hinge and a variable stiffness design method, comprising a spherical hinge main body (1) and an outer layer sleeve (2) sheathed on the spherical hinge main body (2), wherein an annular sealed space (11) is formed between the spherical hinge main body (1) and the outer layer sleeve (2) along circumferential direction, and the annular sealed space (11) extends deep into a rubber layer of the spherical hinge main body (1); an annular stop (3) is arranged in the annular sealed space (11), and the annular sealed space (11) is not fully filled by the annular stop (3); an annular gap (12) is formed between the spherical hinge main body (1) and the annular stop (3) along axial direction, and the minimum radial width of the annular gap is X, with 0.5 mm<X<10 mm. The present invention meets the loading requirement that the spherical hinge needs a small stiffness under a small load and a significantly increased stiffness under a large load and can be limited in time. The present invention can effectively prevent external dust, dirt and even sand particles from entering the spherical hinge, which increases the release space of the rubber, effectively avoids the "buckling" deformation of the rubber, and is favorable for increasing the pre-compression amount of the product, preventing the occurrence of rubber cracks and improving the fatigue life.