Shaft Bearing Elastomer Fold Rolling Motion
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Solution Overview
Problem
Existing shaft bearings for motor vehicle drive shafts face challenges in maintaining high radial rigidity while accommodating axial deflections and avoiding buckling, especially at low speeds, within limited radial space.
Innovation Solution
A shaft bearing design featuring an inner sleeve, an outer body, and an elastomer body with a fold that maintains constant free length, ensuring consistent radial rigidity and preventing buckling through clean rolling motion, with the elastomer body's rolling sections permanently contacting the inner and outer surfaces, shifting the stiffness peak to higher frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the shaft bearing uses a conventional elastomer body design, then it can accommodate axial deflections, but it cannot maintain high radial stiffness and is prone to buckling at low speeds
Solution Approach 1:
The elastomer body is designed to perform a controlled rolling motion during relative movement between the inner sleeve and outer body. The fold transitions from a static configuration to a dynamic rolling action, where the contact point moves along the rolling surfaces. This dynamic behavior maintains consistent free length of the fold, ensuring stable radial stiffness while accommodating axial deflections without buckling.
Solution Approach 2:
The invention changes the geometric parameters of the elastomer body by introducing a fold with specific rolling surfaces. The fold is designed with a free length that remains constant during operation, and the rolling surfaces are configured to ensure that the sum of contact lengths remains constant. This parameter control maintains optimal radial stiffness while preventing buckling.
2Area of stationary object
If the shaft bearing is designed for high radial stiffness with limited radial installation space, then it meets space constraints, but it becomes difficult to maintain stiffness during axial compensation
Solution Approach 1:
The invention transitions the elastomer body's deformation mode from purely radial compression to a combination of rolling motion and axial deflection. The fold's rolling action along the rolling surfaces adds a dimensional aspect to the movement, allowing the bearing to accommodate axial displacements of up to ±20 mm while maintaining radial stiffness within the limited radial installation space.
3Adaptability or versatility
If the elastomer body fold has a long free length, then it provides flexibility for axial movement, but it reduces radial stiffness and allows buckling
Solution Approach 1:
The fold is designed with a specific free length that is optimized to provide sufficient axial movement flexibility while preventing buckling. During operation, the fold performs a rolling motion that dynamically adjusts its configuration, maintaining the optimal balance between flexibility and stiffness. The rolling action ensures that the free length remains constant, preventing the fold from becoming too flexible in the radial direction.
Solution Approach 2:
The invention precisely controls the free length parameter of the fold and the configuration of the rolling surfaces. By optimizing these parameters, the design achieves the right balance: the free length is sufficient to allow axial movement but short enough to maintain radial stiffness and prevent buckling. The rolling surfaces are designed to ensure that the contact lengths change in a controlled manner during operation.
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 achieves high radial stiffness and maintains it during axial deflections, preventing buckling and ensuring high-frequency natural modes are irrelevant, thus avoiding local loads and ensuring compliance with bending radius constraints.
Implementation Method 1
the elastomer body to deform, damping and/or isolating the vibrations transmitted into the shaft bearing
Implementation Method 2
an elastomer body that elastically connects the inner sleeve and the outer body
Implementation Method 3
both rolling sections roll the same distance on the rolling surfaces facing them and the free length of the fold remains unchanged
Data Source
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AI summary
The present invention relates to a shaft bearing (10) for supporting a shaft of a motor vehicle, having an inner sleeve (12), an outer body (14) which surrounds the inner sleeve, forming a gap, and an elastomer body (16) which connects the inner sleeve and the outer body to each other in an elastic manner, wherein: the inner sleeve has a first rolling surface (46) facing the elastomer body, against which first rolling surface a first rolling section (32) of the elastomer body rests; the outer body has a second rolling surface (48) facing the elastomer body, against which second rolling surface a second rolling section (34) of the elastomer body rests; the two rolling sections are connected to each other via a fold (22) which has a free length; and when the inner sleeve moves relative to the elastomer body and/or the outer body moves relative to the inner sleeve, both rolling sections, at the rolling surfaces facing the rolling sections, roll over the same distance and therefore the free length of the fold remains unchanged.