Sealed Joint Assembly Centrifugal Force Sealing
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Solution Overview
Problem
Existing joint assemblies for high-speed propeller shafts in motor vehicles face challenges in achieving reliable sealing and compact design, especially under high operational speeds, where residual out-of-balance issues and centrifugal forces can compromise the sealing effectiveness.
Innovation Solution
A sealed joint assembly with a constant velocity universal joint featuring an outer and inner joint part with ball tracks, a cage, and a sealing mechanism comprising an annular cap, sealing diaphragm, and securing ring, which provides a positive form-fitting connection and secure fixation against centrifugal forces through an annular bead and groove configuration, ensuring reliable sealing and compactness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional diaphragm boot sealing mechanism is used, then the joint assembly can be sealed, but the design becomes less compact and the sealing reliability deteriorates at high speeds due to centrifugal forces
Solution Approach 1:
The sealing diaphragm is divided into functionally distinct segments: an outer collar for mounting on the outer joint part, an inner collar for engagement with the sleeve, and an intermediate sealing portion with an annular bead. This segmentation allows each part to perform its specific function optimally while maintaining overall compactness and sealing reliability under centrifugal forces.
Solution Approach 2:
The annular bead on the inner collar is designed with a specific curved profile that engages with the annular groove on the sleeve. This curved geometry creates a positive form-fitting connection that prevents the inner collar from moving outward under centrifugal forces, ensuring sealing reliability without requiring complex additional components.
2Reliability
If the sealing diaphragm is securely fixed against centrifugal forces, then sealing reliability improves, but the axial length increases
Solution Approach 1:
The mounting function and sealing function are merged into a single integrated diaphragm structure. The outer collar provides both the mounting interface on the outer joint part and contributes to the overall sealing geometry, eliminating the need for separate mounting brackets or extensions that would increase axial length.
Solution Approach 2:
The inner collar with its annular bead is nested within the overall diaphragm structure, with the bead engaging directly into the annular groove on the sleeve. This nested arrangement allows the sealing and fixation functions to be accomplished within a compact axial envelope, preventing outward movement without extending the overall length.
3Reliability
If a secure fixation method is used to prevent inner collar movement, then sealing reliability improves, but the device complexity increases
Solution Approach 1:
The annular bead on the inner collar and the corresponding annular groove on the sleeve form a self-contained fixation system. The geometry of the bead-groove interface automatically provides the necessary mechanical interference to prevent outward movement under centrifugal forces, without requiring additional securing elements, clips, or complex assembly procedures.
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 ensures a compact, reliable sealing effect even at high speeds, preventing the inner collar from moving outward due to centrifugal forces and maintaining secure sealing conditions, thereby improving driveline NVH dynamics and extending the service life of the joint assembly.
Implementation Method 1
even at high speeds such that occur in the propeller shaft in the driveline of a motor vehicle, it is securely fixed on the sleeve and reliably seals the joint chamber. As a result of the annular bead of the sealing diaphragm engaging the outer annular groove of the sleeve, there is achieved a positive, form-fitting connection between said components. It is thus ensured that the inner collar cannot move outwardly because of centrifugal forces.
Data Source
AI summary
A sealed joint assembly includes an outer joint part (3) with outer ball tracks (9), an inner joint part (4) with inner ball tracks (10), torque transmitting balls (6) which are guided in pairs of tracks and held in a cage (7) with cage windows (8). A sleeve (16) is connected to the inner joint part (4) and is coaxially arranged thereto. A sealing mechanism (12) with an annular cap (13) is fixed to the outer joint part (3) and includes a sealing diaphragm (15) with an outer collar (18) connected to the annular cap (13) and an inner collar (19) sealingly connected to the sleeve (16). A securing ring (20) fixes the inner collar (19) on the sleeve (16). The sleeve (16) has an annular groove (33) which is engaged by the sealing diaphragm (15) by an inner annular bead (32) formed on the inner collar (19).